I have a 350 tpi, after swapping to a edlebrock intake and accel runners the rpms usually stick @ 1500rpm in gear. A tap of the throttle will drop the rpms. If you slow to a stop light without tapping the throttle the idle stays at900rpm, with a tap of the gas the idle drops to 5-600 and sometimes stalls after ecm hunts for idle. This problem happens on 2 different tb's, tps as been checked. no binding cables or throttle plates. Would this be a vacuum problem or should I be looking elsewhere? It starts and idles normal.

Thanks

 

I would check your intake manifold for leaks. take some carb cleaner and spray lightly around the intake manifold while the car is running. check for bubbles or air coming from it.