1993 BMW 325 Fluctuating Idle / no power

Engine Mechanical problem
1993 BMW 325 6 cyl Two Wheel Drive Automatic 185k miles

I just got this car for a WAY good deal. Beautiful car!! It is a BMW 325is. It has been through 2 hands before me and has clearly sat for awhile. Spider webs all over under the hood ect. Anyway, It will not idle correctly. Almost dies then revs to about 3500RPM over and over. I'm fairly mechanical so i removed the Air flow meter cleaned it and reinstalled it. No change. So It took me forever to find but i removed the IAC and cleaned it. It was clearly dirty and fairly stuck in one position, i cleaned it and it moves very freely now. (What a pain to get that thing off and back on i might add) I should have checked it when it was off the car by leaving it plugged in and turned the key to see if it moved but like an idiot i did not do that. Anyway put it back together and forgot to plug it in. Car started super hard but when it did start it idled perfectly. Realizing i did not plug it back into power i plugged it in and right back to revving and dropping again it went. Frustrating. Anyway with this AIC plugged in the motor responds quickly and revs fast but idle revs on its own. With it un plugged it idles great but the motor responds very sluggishly , revs slow and the car has no power no matter weather it is plugged in or not. The fuel pump and filter was replaced by the guy before me as the old ones were in the trunk. Can you be of any help? I hate just throwing parts at it . A new IAC for my chevy is 35 bucks, one for this car is 268 bucks. I would very much like to replace the right parts the first time in this (parts are made of gold) car ha ha. Thank you very much for your time and help in advance.