Forgive me as I typically work on diesels and can usually figure everything out but this ones go me stumped
I'm Working on a 1997 Suburban with a Vortec 454.
I smells Rich on idle, when you put it in gear or turn on the AC the engine revs high then calms back down.
when accelerating from a stop the motor stumbles a bit and doesn't not seem to want to rev over 3000 when floored and misses a bit.
the truck was brought to me with a leaky injector.
From further testing that I deducted the fuel pump was weak and the regulator was suspect.
I replaced the Fuel Pump, Filter, Regulator and all 8 Injectors with Delphi or AC-Delco parts.
I also replaced the Mass Air Flow as it was producing strange voltages.
I have not replaced the idle air control or the TPS.
I have not smoke tested the motor so I have di not know if the throttle body shaft is leaking.

ANY Ideas?

 

I may be too late on this but have you checked for any trouble codes? They can be stored even if the CEL isn’t on.

An increase in RPM under load (shifting into gear, turning on AC) is normal.

Have you pulled the distributor cap and checked the condition of the rotor and contacts? What about the spark plugs? If so what did you find?

 

I forgot to reply with my find.
Yes I did all of that, I have autoenginuity software
I smoke tested it and found a decent vacuum leak on the air charge piping