mine doing the same thing i just replace the intake gasket and now it do the bumping and jurking at stedy speeds it did not do this before i changed the intak gasket

 

Would your solution on replacing the fuel pump and cat work on 1991 Blazer with 4.3 TBI? I have the same issues of a rough idle at stop lights, but I think mine also has a drop in oil pressure.

I changed my cat about 4 years ago (I don't know what normal maintenance on that is). I'm sure I've changed my fuel pump on this in the last 5 years of ownership, but I'm not sure what the garage I took it to used for a replacement.

 

Mine was doing that only at 2500 rps and under 30mph and if its cold....I changed out my injector, it worked great for the first few days, then started up again, was told to try cleaning the MAF sensor, I did that and it seems to have helped....ALTHOUGH some times when I turn the car on it says I have no gas and my gas light is on, then other times its full when it is NOT full....just in the last week, Im wondering if this IS my fuel pump, going to try replacing cap and rotor and some other things RATS.

Glad you got yours working again!

 

I think everybody should check out my thread labeled FOUND MY PROBLEM!!!!! and read it all the way to the end because I cured ALL of my bucking and jerking forever by cleaning and relocating splice pack sp423 and new ignition parts plugs,wires,cap, and rotor, but the big culprit was sp423!!!

 

can you post the link to your tread ?

 

A search for "sp423" with an author of "RIFLEMAN" will return the thread.