ive had this problem for a while in which the car would idle little bit above the 500 rpm mark and it would seem to idle great then the rpm would dip a little then idle high then back to 600 and this would repeat until i either put the car in gear or the car would turn itself off. the car was auto before so i didn't really notice this problem as the car would be in drive under load but now that its a manual whenever theres a red light and i put it in neutral the car will idle fine then start to idle high then low so i try to press the gas a little so it doesnt die. ive changed the iac, the rotor and the cap which made the problem go away for awhile but it returned. i also notice that if i turn my steering wheel at a stop (to reverse in a spot) the engine will suddenly idle low the lights would dim and it would sometimes turn off or idle back up. the car is a 350 l98 tbi with EBL installed only thing done in the engine bay is smog removed and ac delete. maybe try adjusting the idle screw? any tips would be appreciated!

 

So i did some runs with the ve learn and i guess it was bogging down at 600 cause it was too rich. i also changed the iac setting to be at a minimum of 600 rpm