Soon after start up idle jumps between 1000rpms to 2000rpms, no engine trouble codes, swapped new Idle Air Control Valve, swapped the PVC valve, clean throttle body, idle adjust did nothing, switch signals to computer all check out, hoses and connections all check out, changed the ECU for one on eBay, with no change in the idle. I did put a large piece of rubber on the intake to block air flow and the car idle settled and continued to run. Now I am really puzzled. Do I have an intake leak? Can anyone help? Two years trouble free record has come to an end! :(

1996 Honda Civic LX 4dr 5spd

Test/replace the Ignition Control Module (ICM) inside the distributor. AutoZone can test ICMs and coils for free.

See if you think the link below describes your situation:

https://www.askmehelpdesk.com/cars-trucks/faq-how-troubleshoot-repair-maintain-hondas-46563-3.html#post260436

I will test it, your post260436 has been very enlightning. But can you explain to me why if I cover the throttle body intake completely the surge settles, and engine continues running? The guys at the shop assure me I have either a vacuum leak, loose intake, cracked manifold.

Thanks

I agree with you that it sounds more like a leak than a problem with the ICM. However, I wanted you to read the link, just in case you thought it described your situation. Use soap and water and see if it helps you locate the leak. Any leak, whatsoever, totally screws up carburetion.