car starts takeoff slugish when it picks up speed at 20 miles runs fine i changed many relays and sensors of all magor my engine is a LT1 5.7
LT1 engine on 1995 Chevrolet Caprice
Your car has On Board Diagnostics level 1 (OBD1) not as good as OBD2 in which you could plug in a scanner and look at live sensor data and look at various sensor performance. I presume you have no check engine light on. It could be many things causing this problem and hard to guess without doing some basic diagnostic tests. Perhaps looking at the O2 sensor readings, checking the throttle position switch and air flow meter readings are a place to start, clean the throttle housing, and try a heavy concentration of fuel injector cleaner in case the fuel injection spray pattern is poor or you have carbon build up on the back of the valves.