1995 Nissan Maxima 251,000 miles, the past two

Clogged fuel. filter.

Sounds like a failed transaxle

You drive 20 miles or use a vehicle for days like
that,you ruined it,period,no relearn will fix internal
damage

Not many transaxle's see 100,000 miles or ten years

put the front up on jack stands and start inspecting push, pull, tug, ****, kick whatever you have to do to find out if anything is loose under the front end if you can't find anything put the whole thing up on jack stands then with the help of a trusted budy have him/her start and put the vehical in gear let idle see if you can hear the rumlbing. then very carfully slide under the vehical and listen. use a vaccum hose as a mechanics stethoscope, or use a long handle screwdriver or prybar to put on suspect bearing housing and listen for the grinding noises.

check your break pads, and calipa. check your wheel balancing and alignment

if you notice it when it is wet out then i would do a tune -up but if not i would check the fuel injectors because they are a very very common problem with these years of cars. i do them all the time.

please give me a repair history and i will try to help.

change the mass air flow meter.You have nothing to lose that supposed to be changed at 60.000.miles

It sounds like either a fuel restriction or clogged CAT. What have you run for tests so far. Were any repairs or maintenance performed prior to this issue.

Have the tires checked for a slipped belt.

sounds like the fuel filter has become almost plugged, have u replaced it in the last 30,000 miles?

You may need a new ECM/computer. This model car is known for water leaking into the ECM from your air box. The drain hole in the bottom of the box gets clogged and after a while, your ECM gets flooded, because the water has no place to go, but onto your ECM, frying vitale circuits. Check your passenger side floor by the feet to see if its wet.