Any luck man? I've sure not had any. Beginning to wonder if the TPS's get dead spots.

 

I have not found the problem just yet. I have a some what clue to what my problem is.
Something still leaks inside the plenum! My cat is defect in some way, whan it's raining outside and that keeps the cat from overheating, the problem stays away longer than when its dry. I'm waiting for a nut kit and a new cat, and I hope thats it.
Maybe replacing the TPS also....

 

I've heard of the TPS going bad on some earlier models. That might be a part to replace just to eliminate the possibility--they only run about $40.

 

I switched out the TPS to a known bad TPS, the earlier defect came back, but the jerking almost went away. It could be that my TPS was defect when I bought it.

 

If you are getting raw fuel into the exhaust (aka misfire or faulty injector) that will cause the Cat to heat up and fail prematurely.

 

Any developments? After checking the timing (base & consistency with the ESC wire plugged and unplugged) with a light I decided to get a reman ECU from rockauto.com and it fixed MOST of the issues I was having. Guessing it was the injector driver that was going bad slowly.

 

Glad to hear you're getting this worked out.

 

I know exactly what you are going through, sorry I dont have an answer but I know this is not a suspension problem or a tranny problem as some have tried to suggest. This problem is not exclusive to Blazers. My 2000 chevy pickup did this, my 96 GMC suburban also does this, my mother in laws 96 blazer does this. It is a fuel problem I am sure. When it is cool outside it doesnt do it right, when there is more weight in the car it does it right? When you are climbing a hill or high spot in the road it does it right? When you are cruising at about 50 or 60 mph and try to ease on the throttle it starts jumping/lunging right? I saw a while back you said it started again with the added weight of your father. The outside temp being higher would suggest the the engine doesnt like burning the warmer air, the added weight or climbing a hill suggests it is asking for more hp or fuel and not getting it or maybe it is but the engine/computer is not adjusting the timming to compensate. My suburban was doing it really bad and I dumped a bottle of the house brand of kragens fuel system cleaner in it and it all went away for about 2 weeks, I think it is a problem with the injectors.

 

BUMP- I was reading through this thread and the exact post above is whats been going on with my Blazer. Has anybody come up with a solution to this problem?

I have changed plugs, wires, distributor cap, rotor button, and TPS sensor, and still nothing. All seemed to help the problem a small bit but still have it. Got the transmission checked out and they said it was fine so it must be a engine problem.

 

I've still been toying with things. My TPS checked out good with a DVOM, but that doesn't necessarily mean it's not at least part of the problem. Backing the timing off a couple of degrees helped out because it seems to make a little more torque that way and therefore requires a little less throttle pressure to motivate the truck down the road. Beginning to think the TCM has something to do with the issue because my hesitation is always near a shift point, and the converter tends to stay locked up too long. Going to check that out this weekend. Still suspect of the CPI injector itself, but I can't seem to find anyone willing to sell me just the injector, as I know my spider assembly is good.