Ill try to be to the point and make this as short as possible.
I bought a 1999 Civic with 85000 miles, very good condition 5 months ago. It now has almost 87000 miles. Everything was fine until about 3 weeks ago....
The car cranks and idles fine upon warm up. Once it reaches normal operating temperature, if I let the car idle for more than 10-15 seconds without any throttle input the check engine light will come on.If I tap the throttle in the least every few seconds or just slightly hold it open when I come to a stop... the light never comes on.

​​​​WHEN the check engine light comes on, the car still idles fine, albeit a little high (1200-1300 or so), but when you apply throttle the RPM's like to get jumpy or hesitant for a moment at 1700 RPM. Also while driving any application or release of the throttle is VERY adrupt and jerky, almost violent even. This is the main symptom. I can cruise along fine, but as soon as I let off the gas or reapply it, it's extremely 'joltey'.
It only behaves like this when the check engine light comes in due to me letting it idle by itself at full operating temp without throttle input for more than 10 secs. I've been riding around for a week very lightly keeping my foot on the pedal at traffic lights, and it keeps the check engine light off.

I had the code pulled at auto one, they said it was the Air idle control valve. Replaced it with a quality replacement and it didn't change anything. I've been Googleing for two weeks and haven't found anyone with this exact problem. I have also already cleaned the throttle body. I'm thinking it's some sensor on/around the throttle body,since the problem only occurs when the butterfly valve isn't touched for more than 10 seconds at operating temp.
Please help! This gremlin is driving me crazy! Sincerely thank you to anyone who took time to read this!!

 

If it were me I would look into the TPS (throttle position sensor) made sure it read what it should at idle and when the throttle plate is fully opened. Some TPS develope dead spots with time (only way that I know of seeing them is on an oscilloscope-no smooth transition between voltages: multimeter is too slow to show this

 

What code did they say was displayed? p0505? If the problem did not improve, the symptoms remain the same, and the code is the same, then something else in the same system is possibly bad, or your replacement is perhaps bad. An open in the wire harness? Dirt in the connector? Post the code you are getting.

 

Check wiring to the IACV that's going to be what your looking for either the wiring or the valve, maybe you ordered the wrong valve or the wiring to the plug is bad.

 

Bad wire harness somewhere, or bad spot somewhere on the ECU.

 

There are two different CEL codes for the IACV. One indicates a mechanical problem, and the other indicates an electrical problem in the IACV circuit.

Have AZ pull the CEL code again. Post the code in this thread.

Knowing the specific code will help to pinpoint the problem.

It would also help to know the engine and model of your Civic.

 

Thank all of you for the feedback! I will have them pull the code again and post exactly what it is. I have checked the wires and connections as far as I can access off the sensor (a few inches til it mates into the harness/corregation). Everything seems OK, I'll just get the code pulled again and let you know.
Thanks, you guys aren't being dicks about my question like another forum I asked....