With a car that's not equipped you can't just put one on as the computer has no place to plug in, nor the programming to recognize the sensor. You'd have to replace the computer and get it programmed. But from what you said about the MAF I'd guess that's your problem. Try an online source and see if you can get one shipped for your specific application. The 318 uses an O2, yours does not. That may mean the MAF on yours may have a slightly different operating wavelength and is sending erroneous info to the pcm when warm causing the problem. When you replaced the element did you soldier it back into place? Other cause may be when the car gets warm the contacts heat up, spread apart and make intermittent contact. Bottom line you may just be best off to try to find a fully functioning replacement from, or for, a 316