I have a 2000 ECSB GMC with a 4.8/4L60E. It supposedly has a 3200 stall and a comp 220 cam. I don't know either to be true. It stumbles off idle and runs like crap, I have had it tuned, but he says that with the code there is a mechanical problem somewhere and it has to be fixed to proceed. It keeps throwing a P0121 code and I have replaced the TPS, the map, and intake gaskets. I have sprayed it down several times trying to find a vacuum leak with no luck. The brakes are also very weak, with a hard peddle. Has anyone had this problem or know what it could possibly be? Thanks in advance.

 

is the brake boost hose on right? or your brake booster is done for.

 

^^^^x2^^^^^

 

That's what i was thinking, but I can unplug it and the truck still surges on idle? I am thinking that this is all one big problem, but I just don't know what it is. Kinda just guessing from here, I don't wanna dish out $100+ unless I'm sure it's gonna fix my problem.

 

Ok, so I don't think that the brake booster is my problem. After doing a little more research and asking around, maybe it could be that the cam in the truck was installed incorrectly and I need to tear into the motor. Somebody please stop me from making a big mistake or wasting time if you know what this could be. The motor doesn't run like it should, but I have fixed the code.

 

"Somebody please stop me from making a big mistake or wasting time if you know what this could be. The motor doesn't run like it should"

Not trying to sound like a dick, but it only takes an hour, start to finish, checking the timing references for the cam. It's a process of troubleshooting; you could have had it torn apart in the time you have read this...lol Always do the free stuff first!

 

Maybe an hour of you have all the right tools already and know exactly what to do. If you've never done it before, I could see it taking much longer.

 

When you unplugged it from the brake booster, did you plug the line so it wouldn't be a huge vacuum leak?

 

Well if I knew how and what to look for, maybe your right. Can you please explain the procedure so I don't waste anymore time and money. Thanks.

 

Yes, I held my hand over the line and it still surged.