My wife has an '00 4 door 4.3l with an automatic. It has developed an issue. I have a check engine on but it's for tank pressure (autozone checked). Maybe a bad gas cap. The issue is it is very hard to start. First thing in the morning it will usually bust off. After you drive it however, then kill it, it will fire, then die. You have to wait about ten seconds then it will fire again and die, then immediately you hit it again and it will usually start. It also began to stumble going up mountains under acceleratioin. I have cleaned the MAF. Cleaned the throttle body and IAC. I cut the cat off cause it was stopped up, put a section of pipe back in place (I know it's illegal, but for now). Still doing it. I don't have equipment to get vaccum reading or codes. I can also hear the fuel pump humming loud....but that's been going on since long before the issue. But I've noticed now at an idle the the hum kinda goes up and down randomly. Any suggestions? OH, I also changed the intake gaskets.

 

It Could be a number of things, my best guess would be to change out the Fuel Pump Since its Making so much Racket already
What did you torque the manifold bolts to when you replaced those gaskets? Just Curious

 

Chuck, I don't remember exactly. It's been a while but I did have a book and went by the torque specs and pattern with an inch lb clicker. On the fuel pump it has been loud since I installed it two years ago. This problem just arose about six months ago.