95 Astro Van idle surge.

[blizzard21967]

Whats up guys new to forum looking for answers. 95 Astro vin W 4.3. Vehicle starts fine runs good after running at idle for about 4-5 minutes sometimes more , sometimes less idle will surge (high idle) at times to 1100rpm then goes back to about 600rpm. It wont do it all the time. Customer had replaced cap, rotor, wires, plugs, new (CARDONE)distributor/new icm module, ignition coil, egr valve, iac valve. Checked fuel pressure KOEO 55-61psi. Checked for broken/leaking vacuum hoses and found none. Scanner detected erratic tps readings.Was able to pull code 22. I replaced sensor and still same problem. One thing I noticed was while viewing scanned readings, TPS % would jump from 0% to 7 % thats when idle would kick up, without pressing gas pedal, in park. None of the actual scanner readings (fuel trim, o2 sensor,iac etc..) changed when problem occured. Any ones help is greatly appreciated.

[old_master]

TPS spike is your problem. Possibly the sensor, wiring, poor connection, or even a worn throttle shaft or bushings in the throttle body. Check it out and post your findings.

Fuel pressure may be a bit low too. KOEO, fuel pump running, pressure should be 60psi to 66psi. Must remain above 55psi for 3 to 5 minutes after the pump shuts off.