Well, the idle shouldn't be changing from spraying around the injector regardless. Something is going on there. Did you replace with metal or plastic intake gaskets? Replace injector o-rings at the same time?

Unfortunately the MAF code you're getting is a catch all. It can mean the MAF is messed up, or... vacuum leaks, unmetered air entering the engine, all that good stuff. Only way to know would be to watch the MAF and see how it reads as the car runs. However, unplugging it and the car running good is a sign of a bad MAF.

Yeah, the '98 is that one. However, I managed to get a salvage title for it. It's even insured and road legal atm, it just has some issues I need to work on and a bad vibration I've got to fix in the front end.