My 96 w/ 4.3 V8 has been acting up lately, almost seems to change according to what gas I get (??) - seems a little better with the middle/higher gas, worse with regular. Idles fine, but when you accelerate it sometimes surges back and forth and tends to hiccup/misfire a couple of times, especially when starting from a stop and/or passing. It's much worse with the AC on, seems about twice as slow. Seems to be different every day, sometimes barely noticeable and other times it's straining away. Also the 1-2 shift whistles, the harder you accelerate the louder and longer the whistle. Anybody else have this problem? Car has 77K miles. Thx.

My 96 w/ 4.3 V8 has been acting up lately, almost seems to change according to what gas I get (??) - seems a little better with the middle/higher gas, worse with regular. Idles fine, but when you accelerate it sometimes surges back and forth and tends to hiccup/misfire a couple of times, especially when starting from a stop and/or passing. It's much worse with the AC on, seems about twice as slow. Seems to be different every day, sometimes barely noticeable and other times it's straining away. Also the 1-2 shift whistles, the harder you accelerate the louder and longer the whistle. Anybody else have this problem? Car has 77K miles. Thx.

have you done any tuneup work on this vehicle.? .Do you do the work on your vehicles ?

with the vehicle this age plug wires,vacuum lines,all distributor componets,coils,connections at distributor/coil.

fuel filter every 30-40,ooomi. plugs at 50,ooomi.

if it still does it after you have replaced these parts , and it still does it this will help..find where else to look.

Has the Opti been serviced yet?

I don't think the Opti has been serviced yet. I replaced the fuel filter a couple of months ago, when he put the old one in the pail the gas that came out was somewhat swirly-looking. Have not done the plugs or wires yet.Is there a vacuum diagram somewhere on the web with all the vacuum lines?A few things I noticed over the last few days: One is that is seems to start happening after I've been driving for a few minutes, seems somewhat smoother when it's cold, and then it starts to act up after a few minutes of driving. Also, I when I put it in Drive with the door open (worse in Drive than in Park) to listen to the engine, every time it hiccups I can hear a faint metallic "tink" noise, like someone tapping their fingernail on a piece of metal. A very faint sound, almost can't hear it unless you are really listening.

I have a 94 caprice lt1, was having the same problems,Took it to the local GM dealer and talked with a mechanic that used to work for the at the State Police vehicle maitenace facility and worked on many caprice's ( I found a gold mine!) Check the positive post located by the fuse box under the hood , it may not be tight enough. If your not getting enough power to your distributor it will give you the simptoms you discribe. You can replace the post very easy and very cheap. If that isnt the problem it may be your dist or plugs and wires.. Good luck

I don't think the Opti has been serviced yet. I replaced the fuel filter a couple of months ago, when he put the old one in the pail the gas that came out was somewhat swirly-looking. Have not done the plugs or wires yet.Is there a vacuum diagram somewhere on the web with all the vacuum lines?A few things I noticed over the last few days: One is that is seems to start happening after I've been driving for a few minutes, seems somewhat smoother when it's cold, and then it starts to act up after a few minutes of driving. Also, I when I put it in Drive with the door open (worse in Drive than in Park) to listen to the engine, every time it hiccups I can hear a faint metallic "tink" noise, like someone tapping their fingernail on a piece of metal. A very faint sound, almost can't hear it unless you are really listening.

you need to carefully check those vacuum lines especially the PCV hoses..these parts crack and fail at 10year age..when cold the engine is running in rich mode...this covers the vacuum leaks..then when it gets at operating temp the vacuum leaks affect performance..

if you don't know anything about this bring to someone who does...

also your distributor needs vacuum of the correct volume to continue to operate correctly...if it is lost your 500.oo distributor is destroyed...not to mention the cost to replace !!!!!

Impcyl, are you talking about the positive battery cable-to-battery connection?

Does anyone have a pic of where the PCV valve and/or vacuum lines is located? I think I found it, not sure, does it have a metal tube attached to it and go to the middle of the drivers side valve cover?

About that battery to fuse box connection, i went out and checked, it does seem a bit loose, but that's the plastic cover on top. If this was the case, would tapping on the plastic cover tend to cause it to sputter, and would it have any other symptoms? Also, how does this cover come off so that I can see the terminal?

One more thing I noticed is that it tends to sputter the most when giving a sharp push on the gas pedal, such as passing someone or climibing a hill. Again, much worse in D than in Park.

About that battery to fuse box connection, i went out and checked, it does seem a bit loose, but that's the plastic cover on top. If this was the case, would tapping on the plastic cover tend to cause it to sputter, and would it have any other symptoms? Also, how does this cover come off so that I can see the terminal?

One more thing I noticed is that it tends to sputter the most when giving a sharp push on the gas pedal, such as passing someone or climibing a hill. Again, much worse in D than in Park.

if the battery to underhood fuse connection plastic cover is an issue for you,,you best get hands on help fast...