1988 Buick Century Service Engine Indicator light

1988 Buick Century mileage: 130,000. Recently, the Service Engine Indicator light came on. The diagnostics revealed a code 34, which points to the Mass Air Flow sensor. However, about 10 months ago, the same thing happened and the mechanic replaced the following: Mass Air Flow sensor; Computer Module; two (2) "PROMS" (chips?). The mechanic stated that the bad computer module caused the MAF to go bad. Since these parts are out of warranty, I'm back to square one. The symptoms include: rough engine, a/c suddenly doesn't put out cold air, engine gets real hot. 1. Is it possible to determine whether the problem is the MAF, Computer Module or both? I am minimally mechanically inclined, by the way. 2. What are the two "PROMs" and would I have to order them separately? 3. Where, on this model, is the computer module located?