So I need some help from fellow stangers so I've been diagnosing a idle issue like a misfire or ruff idle on my 2000 mustang GT I checked for code but none found I've tested the EGR and found it bad and replaced due to not holding pressure but still no change I also cleaned the MAF sensor and still nothing also cleaned throttle body and plenum and still no change I also removed spark plugs and re-gaped still no change also cleaned IAC valve still no change also did smoke test to check for intake leak but only found abit of smoke coming from the small black cap on top of the IAC valve don't know if that's normal due to the fact that it spins freely has any similar issues with your cars? Need help its driving me crazy, don't like my car running bad.

 

Probably coils. Mine acted like that and It did not throw a code. Changed the coils and problem solved