Engine Performance problem
1987 Chevy Suburban V8 Four Wheel Drive Automatic 150k miles
My 1987 Suburban will not maintain a steady idle and a miss at idle. It idles up and down, but when driving it runs great. I suspected a vacuum leak, checked and no leak found, replaced air intake valve, map sensor, spark plugs and wires, egr valve, changed throttle body and gasket.
Any help would be greatly apperciated.