Jimmy acceleration problems

[Bagel191]

For the first 30 secs its runs great then under normal acceleration it starts running very rough. If I punch it it seems to clear up. If in nuetral it seems ok to just under load. Ive just change the temp sensor thinking the choke was staying on (didnt work) I also changed the O2 sensor(also didnt work) the truck has new wires plugs cap and rotor. The fuel pressure seems to be ok 2. CAN ANYONE HELP PLEASE.

Thanks in advance

BAGEL

[BlazerLT]

what year, engine?

We need all information

[Bagel191]

its a 1990 model 2 door 4x4 automatic with a 4.3 V6

[BlazerLT]

Check your timing.

Remeber to remove the timing wire from the computer under the dash.

The wire to disconnect is a brown and beige wire running under the carpet under the glove box.

Remove it, time the vehicle to zero with a timing gun and then reattach the wire.

[Bagel191]

I'll try it and let you know. If anyone has any more suggestions I'll be more than happy to listen...

[Bagel191]

Timing is dead nutz at 0. fuel pressure is perfect. Someone told me it could be the throttle position sensor? Any know anything else it could be or something else I can check?

[BlazerLT]

Did you disconnect the timing wire while timing the vehicle with a timing gun?

[Bagel191]

YEs the wire thats under the glove box. I also looked it up on ALLDATA to find out were it was.

[Bagel191]

Anyone have any suggestions

[BlazerLT]

Fuel Pressure?

Ever changed the fuel filter?

[blazes9395]

I' am just wondering if you found the problem, if not, is the SES light on?

[Bagel191]

I had the fuel pressure tested and it was good.
SRS light is not on.

[BlazerLT]

What pressure did it show?

[Bagel191]

If i recall it was like 14psig. I looked it up on all data to get the tolerance and if im not mistaken it was 13-18 and i know it fell in that range. But remember when i first start it i can drive about 2 or 3 blocks and it runs great. I had another suggestion from a friend who said that Cat could be plugged????? but im not sure how true that is...

[blazes9395]

Did you check the operation of your EGR valve and the system? An easy way to tell if there is a problem there, is to disconnect the EGR valve. Pull the vaccum line that goes to the valve only, not anything else. See what happens.