2000 gmc jimmy 4.3,4wd. New head gaskets,intake gaskets,plugs,cap rotor,tps,new trans filter and 1-2,3-4 control solenoids. My problem is when I'm in cruise going 60mph the rpm is only 1500 and once I start to climb a hill it studders like the engine is missing, no codes at all. Also the trans was rebuilt at 120k it now has 160k beast sunshell,transgo shift kit. Replacing the fuel pump and sending unit in two weeks...ish, no clue as too how much gas is in it. Any help would be great!

 

What did the RPMs used to be? What is your differential gear ratio?

 

No idea on both, had it for 2 weeks before the intake went **** up. It shudders like a bad TC, but I put it in P held the brake and gave it a little throttle and it didn't shudder. It's pretty odd. All the ignition is new, . I guess we shall see what happens when it gets a new fuel filter and Delphi pump. Anyone know what psi the fuel system is supposed to be at? This thing is a damn money pit. I miss pre 80's GM stuff.

 

Bad cat perhaps? O2 sensors.....

 

so i remember when i purchased the rig someone had plugged the PCV port on the valve cover and had plugged the line going to it, i noticed that the pcv valve was rattling like a pocket full of change(I replaced it with one awhile back). so i pulled it and plugged it up again to see the diff. Anyway not much changed and now even with or without it it has trouble starting, it did throw one code for the MAF , i cleared it. My assumption is that either the exhaust valves, one or more are burnt, bad EGR, or the disty is shot. I dont know how i would check the EGR on this thing to see if its stuck open or closed. I ran a scan while driving home, about 20 miles, i noticed the vacuum fluctuated drastically when at 3k and doing between 50 and 60mph. Im tired of throwing parts at this thing so im planning on cleaning the egr and seeing if that helps any. Otherwise its a comp test to see if i have a burnt valve(s) or not. if not then its on to the distributor.