355 Where to Purchase 2 MAF Sensors?

They are unavailable. You can have them rebuild here: https://www.fuelinjectioncorp.com/

But have you checked the ECUs for codes. If an MAF is bad swapping sides won't fix anything. It would just move the problem to the other bank. If it did fix it, then it might just be a bad contact.

Read the codes.

 

I hate to even suggest this, because I have no idea of the quality...

...but RockAuto shows a listing for the 1995 F355 MAF sensor. $55 each, might be worth a try?
More Information for TPI MAF1199 (rockauto.com)

There are other factors at play that would kill a bank of cylinders, too...like the thermocouples that protect the converters. So the MAF might not be the issue.

Pulling codes from a '95 pre-OBD2 car will also prove tricky to the uninitiated.

 

if the car has sat 20 years then you really ought to drop the engine & change the cam belts ASAP. Avoid running the car because if a cambelt fails, which is a possibility after standing so long, you will be in a whole world of financial pain.

“While you’re in there” there are a ton of things you should do in addition to the engine out service. The cost for service parts isn’t totally nuts, so it is absolutely worth doing. I would also thoroughly clean all electrical contacts — assuming the car was in perfect working order when it was last used, and stored in reasonable condition, then there is a fighting chance the car will run well after a good service. That involves dropping the engine, but don’t be intimidated. It is totally doable if you have some skills and there are loads of threads covering practically every repair procedure you can think of.

Until getting the basics sorted and creating a baseline, you could be chasing your tail for hours looking for various air leaks, loose connections, sticky actuators, gummed up mechanisms & what not.

 

I bought allot of parts for my previous 1995 F355 GTB from both Rock Auto and Ricambi USA. Some OEM parts were found on eBay at a good price. You may also want to make sure your headers are not leaky by removing and doing a smoke test. Leaking headers will result in the engine running rich and can cause damage. The car would run hot and result in a 1-4 or 5-8 code. The exhaust smells sweet in this case. You could make a button yourself for the ECU code reading. It appears from my F355 to be just a single throw push button with 2 wires. The dash light flashes and pauses which you can then decode into what it means. My F355 manual had the list of codes (example : P1212 = 1 flash, pause, 2 flashes, pause, 1 flash, pause, 2 flashes long pause and then repeat).

Which city/state do you live?

 

Buy some MAF cleaner and clean the element.

There are cheapo replacements available on Amazon. I have one--you could try putting one in and seeing if that is indeed the problem before forking out the cash and expense for a rebuild.