Rep Power: 0

Ok let’s start with last Friday night, car was having a misfire problem when I kept a steady speed and a CEL came on with codes P0300 - P0304 (misfire) I changed out the coil packs, spark plugs, cleaned egr ports and egr valve and did a compression test (compression for all 4 is 159-162) and the problem went away and CEL turned off.
saterday morning, idle high (1,500 rpm) and CEL comes back on with codes P0300 - P0304 (Misfire) and code P1505 (PCV Air Leakage) I check for vacuum leaks couldn’t find any so I changed the PCV and made sure the hose on it was tight, CEL went away.
Tuesday morning (when I posted this) my car starts fine and after about 3 minutes of driving the idle starts surging when I release the clutch (Manuel car) and shortly after my CEL comes on, I start to drive to autozone to get the code scanned to see what’s new and my car flips out, ok let’s say I’m in second gear accelerating slowly (everything is fine) I let go off the throttle (red stop light) to slow down and my car jerks and slows down to 1,500 rpms while I’m still in gear (almost like i breaked really hard and let go at around 1,500 rpms) at this point I’m scared to drive the car so I try to keep a higher rpms keeping a steady speed, I pull up to autozone and go out of gear to park my car (I’m now in neutral) and the rpm is hovering at 1,500 and it’s jumping rpms like it’s hitting the redlining rev limiter but only at 1,500 rpms, I turn car off and go get it scanned, over codes P0300 - P0304, P1505, and a new one P0505 (idle speed control system). at this point idk what todo, I start the car and it starts perfectly fine, I start to drive home and it starts doing it all again, I park and left the car as is, now I’m here posting this for an answer. Could it be a bad computer?

 
Rep Power: 211

Possibly.

Have you been resetting the ECU after replacing parts?
Have you inspected coil packs wiring harness for breaks?
Have access to a live-data reader for fuel trims and sensors voltages?

 
Rep Power: 0

Yes I reset the ECU And inspected the coil pack wires for rips, also did a multimeter test and was all good, and no for the live data reader what is that exactly?

 
Rep Power: 119

Not a common issue, but fluctuation in fuel pressure could also cause idle issue / misfire / and wonky drivability.

 
Rep Power: 211

There's several types of live data scanners that include a freeze frame function. They show live data when the engine is at operating temp, idle and under load. Examples: short and long term fuel trims, o2 sensor voltages, fuel pressure, various sensor readings. Here's one example that's inexpensive and bluetooth..just download Torque app to your phone:

Read related for the P0505 and P1505: https://www.civicforums.com/forums/3...505-p1505.html

First:
Remove and clean IACV: Idle Air Control Valve...use brake cleaner spray to clean inside the IACV and the screen/gasket
Remove and clean the throttle body. If that doesn't solve it then consider trying a used or new purge valve as mentioned in that link.

Any sort of buildup on spark plugs?
Spark plugs gapped correctly?
Checked mechanical timing to see if cam or crank is out of position at TDC?

 
Rep Power: 0

No buildup on spark plugs and they are tapped correctly. What I did notice when I was cleaning the iacv is that when I sprayed the brake cleaner inside there would be a weird clicking sound coming from it as if the valve was opening and closing, sounded like it was loose so I shook it close to my ear to hear that sound again and nothing.. I then spray more cleaner and it starts clicking again (only does the clicking when I spray the cleaner) maybe I need a new iacv?

 
Rep Power: 211

Testing: Use a set of alligiator clip jumper wires and apply 12v to IACV directly from car battery: