Max2107

No CEL, but got pending codes for P0300 (Random Misfire) and P0507 (IAC System RPM Higher Than Expected).

MAF and Throttle Body recently replaced.

Coils, plugs, dirty precat? Thoughts?

maxiiiboy

You got the right suspects.

The procedures for testing coils and spark plugs have been published on this forum. You should be able to search for them. I am not sure how to identify a clogged pre-cat; I would be looking for unusua/abnormal temperature.

BigLou55

iTrader: (6)

did you perform an idle relearn after replacement?

Max2107

I attempted it a couple of times, but unsure if I did it correctly. I know it could be a factor.

Ghost_54

iTrader: (13)

Throttle Body recently replaced, I would start here to make sure that there is no air leak as that would cause an irregular idle (also I sure hope that the throttle bodies butterfly was not touched or move by hand as they are very sensitive) resulting in the p0507 code ... The p0300 can also be a result of the above but it could also be caused by the VTS (variable timing solenoid) which has a very narrow passage way which you oil travels through and it can get clogged by dirt and other crap that may be in your oil crank case, this can take a few oil changes to resolve (if you do your own changes make sure you let the oil drain for as long as possible - an hour or more if possible - to get out as much from the bottom of the pan as possible) do this a few times to help clear the [possible clog of the VTS.