MAP or other?

hello, I am having a problem with my 89 4.0 stick mj. When I was off at basic i let my buddy drive my truck around when his was in the shop. It ran great until one day it wouldn't start. they changed the fuel pump and now it will start but it runs really rough and when i put it into first it dies. It will run in reverse but it spits and stumbles the whole way. my 86 xj did the same thing and it turned out to be the MAP. my brother said that he swapped the map out of his (parts) 89 4.0 auto xj and said it still did the same thing. he claims it was a new sensor about 2 months before he parked it and it hasn't run in over 4 years. now that i think about it the fuel pump was a "new" pump also out of this parts xj but im not sure. Is there anything i can do to check the map to see if its still good? same for the pump? any thing that would keep me from running back and fourth to the parts store and doing the blind parts swap boogie. I am stationed at Ft Irwin and for those of you how havent been there, its 47 miles the the nearest parts store. so any help to guide me to the answer the first time would be much appreciated! thanks for the help and sorry for the long post

A common problem is a split vacuum line running from the throttle body to the map.
And yes, you can check out the MAP's operation using a digital volt meter.
The fuel pump can be checked out using a pressure gauge screwed into the fuel rail--there's a test port on the rail for that function.

45 mile jont to the parts store? ouch. & i thought i had it bad for having to walk 4 miles to my closest one that i trust. (got one about 3/4 mile, but i dont like/trust it).