I'm stumped :whiteflag . I'm getting VERY bad MPG out of my truck and it seems like i'm not runing on all cylinders. I'm sluggish and I have some stuttering when I'm accelerating. My plugs are a week old and my O2 is a week old. I replaced my wires yesterday (4/15). my cap and rotor are in good shape and were replaced about 8 months ago. My timing is around 10 degrees BTC. at idle my engine seems fine. we put a vacuum tester on my EGR and it killed my engine. I also pulled the cap off of the "control solenoid" (it has two vac lines on it and its next to my coil) and plugged the little hole on the top of it with my finger and it killed my engine. I didn't know the EGR could kill an engine when I did things like that. Could my knock sensor be a cause. I'm also blowin black smoke when I goose the throttle when i'm just sitting there at a park. want to put a pressure test on the cylinders to see if I have bad compression. is there any other sensor that i should consider checking or anything else i could try. its driving me nuts :banghead . thanks for any help.