Idling problems on '95 S10 4.3 Z

Ok, so I continue to have this problem and may have posted it here before but can't find the posting:

As many already know, I have a '95 S10 pickup w/4.3 Z, Manual trany, and manual 4x4. It has had a problem with the rpm's for the past couple of years and have never been able to find the reason. It idles just find when not moving, right around 800 rpm. Once you start going and shift through the gears the engine doesn't want to slow down. When cold it will not go below 1800 rpm's untill the truck is at rest. Once warm it will go down to about 1100 rpm's but this takes a long time and I find the cluch pulling the engine rpm's down at each shift unless I wait a bit between shifts. Again, once at rest the engine will go back down to 800 rpm's. My vacuum lines are new because I just replaced the intake manifold gaskets. I have also tried replacing the idle air control valve, "throttle position sensor", and checked the EGR valve (which was also cleaned a little). I am getting right around 20 Hg of vacuum at idle right now too. To see if it is added gas or air I was thinking of connecting my vacuum gage up inside the cab for a while to see what the vacuum is when driving around. Shouldn't it be lower if the engine is getting extra air but higher if extra fuel without the air? Thanks for the help and sorry for the long inital post.

So no one has an idea of what could be wrong with my truck. Come on guys, throw me a bone here.

Did it do this prior to the gasket job on the intake?

Do you have cruise control?

Is it possible that the cruise control is activating (partially)?

If so, have you disconnected the cruise ?

Check at the GM dealer for a TSB on this problem. There might be a prom update for the ecm

Ok, so I continue to have this problem and may have posted it here before but can't find the posting:

As many already know, I have a '95 S10 pickup w/4.3 Z, Manual trany, and manual 4x4. It has had a problem with the rpm's for the past couple of years and have never been able to find the reason. It idles just find when not moving, right around 800 rpm. Once you start going and shift through the gears the engine doesn't want to slow down. When cold it will not go below 1800 rpm's untill the truck is at rest. Once warm it will go down to about 1100 rpm's but this takes a long time and I find the cluch pulling the engine rpm's down at each shift unless I wait a bit between shifts. Again, once at rest the engine will go back down to 800 rpm's. My vacuum lines are new because I just replaced the intake manifold gaskets. I have also tried replacing the idle air control valve, "throttle position sensor", and checked the EGR valve (which was also cleaned a little). I am getting right around 20 Hg of vacuum at idle right now too. To see if it is added gas or air I was thinking of connecting my vacuum gage up inside the cab for a while to see what the vacuum is when driving around. Shouldn't it be lower if the engine is getting extra air but higher if extra fuel without the air? Thanks for the help and sorry for the long inital post.

IAC Valve

Idle Air Control Valve, remove , clean and reinstall.

Reset the computer so the computer can then relearn the idle.

As I have already stated, I already replaced the IAC valve and reset the computer a number of times over the past year from doing work on the truck. Yes, the problem was around before the intake manifold gasket which I did just two weeks ago. This problem has been going on for about two years now and I am running out of ideas. I have great vacuum, 20 Hg at idle, and have replaced the vacuum lines just in case. Also, I don't have cruse control. I have searched for a TSB with no luck on this subject. Thanks for all the responce and I hope more come.

Talk to the GM dealer about this problem. I remember that high Idle problem with the standard trans but can not remember the fix other then there was a prom update that cured it

As I have already stated, I already replaced the IAC valve and reset the computer a number of times over the past year from doing work on the truck. Yes, the problem was around before the intake manifold gasket which I did just two weeks ago. This problem has been going on for about two years now and I am running out of ideas. I have great vacuum, 20 Hg at idle, and have replaced the vacuum lines just in case. Also, I don't have cruse control. I have searched for a TSB with no luck on this subject. Thanks for all the responce and I hope more come.

Did you spray TB cleaner into the hole where the IAC installs into? That can get clogged up too.

Also, if you don't have any cruise, you have a vacuum leak somewhere.

Did you check to see if the hose going to the vacuum ball was on?

BlazerLT, do you read what I write before responding. I replaced all, and I mean all, vacuum hoses while doing my intake manifold gasket with no change. Also, how would I have a vacuum leak with both the idle sitting right where it should and 20 Hg at idle. It also snaps to just above 0 Hg when reved to 2500 RPM, jumps to 25 Hg when let off, and goes back to 20 Hg. All this is per OEM spec. according to my manual.
Firplug, I will call the dealer and check on that. Thanks for the help.

BlazerLT, do you read what I write before responding. I replaced all, and I mean all, vacuum hoses while doing my intake manifold gasket with no change. Also, how would I have a vacuum leak with both the idle sitting right where it should and 20 Hg at idle. It also snaps to just above 0 Hg when reved to 2500 RPM, jumps to 25 Hg when let off, and goes back to 20 Hg. All this is per OEM spec. according to my manual.
Firplug, I will call the dealer and check on that. Thanks for the help.

Good luck with your problem.

I will help others that aren't as rude as you.

Hey man, you get on peoples' backs all the time. In fact here is a quote by you from another thread I started: "Man, I swear, why are people giving advice when they don't even know what to do." I am just saying you should read the postes a little clearer because you were telling me to do things I said had been done. I just hope you are a little nicer to people in the future knowing that we all make mistakes and most everyone here are really trying to help.

BTW Firplug, I contacted my local dealer service department and they said my truck's computer will keep the RPM's from droping some because of emisions. I guess a lot of people have complained about it due to the difference in how most other cars with manuals act. He said if it is keeping RPM's up too much I could try the temp sensor. If it is reading low the computer will run a little rich to compensate. Thanks for the help guys.

Hey man, you get on peoples' backs all the time. In fact here is a quote by you from another thread I started: "Man, I swear, why are people giving advice when they don't even know what to do." I am just saying you should read the postes a little clearer because you were telling me to do things I said had been done. I just hope you are a little nicer to people in the future knowing that we all make mistakes and most everyone here are really trying to help.

Kiss my ASS

I answer close to 100 or more posts a day not including the PMs I get so if I miss something from time to time, so fuckin be it.

It is assholes like you that jump all over me when I miss one thing that fuckin pisses me off.

Like you are Mr. Perfect or something.

Good luck with your truck, hope you never find the problem. People like you deserve engine troubles like this.

Man you just don't get it do you. I never used any profanity, never got fired up, just stated a simple fact and you have to work yourself up. I said "we all make mistakes" and ment all as in you, me, and everyone else here. I have seen you bash people's posts here numerous times with little regard. Try to be a little less critical of people and remember they are just "trying to help." Thats all I am trying to say.

No matter, good luck, I am not going to trash your thread.

Hope you find your problem.

When you come to a stop light and push in the clutch how long does the rpms stay up and what rpm is it. Also if you take it out of gear and let out the clutch does the rpms still stay up??

If I push the clutch in and come to a stop the RPM's will drop to idle right around 5 mph. The idle has always seemed to be fine when stoped but when driving the engine won't drop RPM's very fast, if at all, between shifts. From what I can figure it must be a computer controlled problem, what do you think?

There was a prom update but I dont think it did anything to help much. Ok idle high between shifts is a normal for that beast.