Hey guys. I have a 2000 sunfire 2200 5 speed. Has 150k miles on it. It doesnt have much power accelerating at all. Fast lopey idle bounching between 850 and 950 rmps. When you floor it the power drops off to nothing the moment you hit 4000 rpms and bogs like the fuel just got cut off. Ive changed the fuel filter, plugs and wires, and air filter is clean. Good compression check too. Im guessing ether a clogged cat or a bad egr valve. I dont believe its the fuel pump. Its been going on way too long to be the pump. And the pump chimes on with a nice and strong humm. Any ideas???

Also i figured i would add. There is no check engine light on and when i checked for codes anyways there were none.

Update. Chopped off the cat and put a pipe in place. No effect. Also changed the MAP sensor. No effect.... Checked for vaccum leaks thoroughly. None found. HEEEELP!!!!

Check fuel pressure at idle and when accelerating and see if it's within spec

Checked fuel pressure. It was good. Then i got to thinking. Maybe it has jumped time. So i bit the bullet and got me a timing set and appropriate gaskets and rtv. When i pulled the cover off gyess what i found. A newish timing set was installed. And the timing mark was off by two teeth on the crankshaft cog. I also noticed that the factory paint mark was marked on the tooth over the keyway instead of the timing dot. So it was a combination of a factory error and an in experienced mechanic. Needless to say i went ahead and put the new timing set in, properly lined up the marks, and put it all back together. The sunfire is running like a new one now. Glad to have it fixed. Hopefully this post will help someone who has a car that has jumped time though.

My guess is cam timing. Specifically timing chain &/or tensioner.