I checked schematics as far back as 1997 and quit looking FSM is the best, but even they have some contradictions in their descriptions of how certain systems work. CKP & CMP data usage for misfire detection is one of them. Mitchell runs a fairly close second, Alldata is fair, Chilton & Haynes... not bad if you need to learn how to change the oil... pretty much a waste of a good tree

 

Had one once that had a wire pinched at the back of the intake, near the distributor-maybe allittle towards the tranny dipstick side. Don't think the tach was pegged...but I think I got an SES lite that led me there. It would only take a moment to look either by your naked eye or a scope or a mirror...good luck..do also think if you knew someone that could do a sweep (as previously stated), that may correct it..(if so require no further looking)..Jerry