1984 Corvette that'* been converted to a 1986 Tuned Port Injection, converted the ECS and all the wiring. The engine idle varies as much as 200 RPM, but usually closer to 100 RPM.

Welcome to GMF! Sounds like a vacuum leak. Check all the vac hoses for cracks, or bad gaskets. If its not that, it could be spark plugs or wires getting bad.

engine was rebuilt, all vacuum lines are new, plug wires new, everything.

hmm. What about the fuel pump and filter, are they new as well?

Yes, but that TPI is used along with the fuel pressure regulator. I seems fine at anything above idle, also, no codes. Could there be something with the fuel pressure regulator?

Thread moved into appropriate section for better visibility.

test the fuel pressure but a rough idle is generally a vacuum leak i would b checking for gasket leaks worked on a 73 vette that had a loose intake manifold. do you have a idle air control on the throttle body?

Yes and it'* been changed.

i cannot recall does it have a MAP sensor..i actually think tpi is a MAF in the intake tube?

yes it does and it'* in the tube.