92 3.9 had a BAD skip n shake.Had a bad injector so replaced it.Cap rotor n wires seemed ok and was getting pretty good spark and great compression at 150-180psi on each cylinder.Several hours of reading here I came across a post where someone had a brand new cap that was bad.I went ahead and changed cap rotor and wires and BAM!!! Fixed the skip.NOW I got to play with timing as I pulled the distributor to check for damage but engine sounds MUCH better than it did.Tackeling the timing issue tomorrow and I think I got it licked..Couldn't be happier..I want to thank all those who helped me look for things to check and all who posted fixes on here..What an awesome site for DIY's...

 

I had a chevy like that where I checked everything, and replaced the usual suspects, only to finally check the timing and whoops! the base timing was waaay off! Once that was fixed, it ran like it was new.