I'm thinking I have a bad MAF sensor on my 89 TPI 350. I'm unsure on what to do. Should I buy a new one? If yes, what's the cheapest place to get it from? And what brand? Or should I buy a used one?

Well, you have 3 options.

1. Find someone with a known working MAF.

2. Learn how to troubleshoot the system.

3. Keep spending money until you get bedrock.

I dont like the used/remanufactured MAF's myself, but just
because I had a bad experience, doesnt mean you will. I prefer
Bosch OEM replacements, for peace of mind.

They are 400+ dollars last time I checked (new). the Cardone
remanufactured are far less cheaper, you can get them at O'reilly,
Advanced, NAPA and the like.

Damn I'm really unsure on what to do. My car has been idling rough but it also releases smoke and small amounts of water with a bit of oil out the exhuast when I rev it. I'm thinking I have something else wrong other than the MAF sensor. Or could the MAF be causing the oil and water out of my exhuast?

MAF just senses air flow so your ECM knows how much air is coming IN. that's it.

you can disconnect the MAF to force base timing and fuel, see if that helps.

the oil coming out of your exhaust is something else, probably from the cylinders. look into that. what color is the smoke? blue = oil burning, white = moisture/water/coolant, smell test, look for your oil/coolant levels lowering. black smoke = too rich fuel mixture.. now THAT can be related to your MAF and/or o2. requires more trouble shooting.

go to the parts store and rent the tool that pressurizes your cooling system, could be a head gasket. See if your cooling system holds pressure

Are you getting any SES lights? Have you checked for SES codes. 33 and 34 are MAF related. Unplugging the MAF, if the car runs better, then it is possible that the MAF is bad ( or the relays or wiring). Sounds like with the stuff coming out your exhaust, that it might be something else, like a head gasket. The advise to test your coolant system is a good one.

Well I have a code 32 which is related to the EGR I believe, could that be the cause of the smoke and oil?

I also have a code 34 which is related to the MAF, should I replace the relays before I go and buy the MAF sensor?

One more question, is a MAF sensor the same on a 5.0 and 5.7?

Affirmative. Replace the relays, and make sure you get the correct
ones. Take them with you, NAPA was pretty good about its selection.

I'm gonna replace the relays then see what happens.