those animals charge 150 just for checking...
And you want us to give you a magic bullet, but there isn't one. We're telling you
HOW to
find the problem, but you have to roll up your sleeves and do the work.
No one can tell you to simply replace a $5 sensor which is easily accessible from the driver seat, which is what you want to hear.
Incidentally, consider that maybe this is why experienced techs get $150/hr. Crazy thought, I know.
I'd start by doing a TON more research. Google the piss out of it, read threads on several forums that are even tangentially related. Watch several vids. The information and tools are out there, but you're going to have to compile them in a manner that finds your answer. Think of it more like college than grade school.
Since the concensus is KS (knock sensor), focus on that. How do you test it, how do you access it, what are the wire colors and where does the harness run?
Also --
and I don't mean this to be insulting -- based upon the questions you've asked thus far this might be over your head. If you have to pull intake(s) and conduct electrical testing you may wind up with your vehicle in pieces and break more things along the way. Consider how long you can have the vehicle down while you learn.
Based upon your username you may want to sell it and buy a TBI Chevy or EEC-IV Ford. Those are rudimentary EFI with very few sensors. Or go way back to carbs.
