86 pa ..wont stay running

hello every one , ive been reading these post for about 6 months now they helped me fix my crankshaft sensor afew weeks ago just by reading posts...now i have a problem.
4 days ago i had to put in a new drive ax on drive side(allready replaced pass side) in the midst of that discoveredmy ball joint was dead frozen in place,i angled grinded and banged that off. ran for a few days then all of a sudden battery dead after days of chargin just bought a new battery car now will start but wont stay if i put it in gear (D)it sputters backfires i was trying to give it gas but the pedal felt like the car was offthen as im holding it down it will rev then almost die then coast like its fine (maybe5 sec)then back to the same thang backfireing sputtering then die. as far as sensors i have not changed anything the reason ithas two new drive ax, new hubs,new alt,new harmonic bal(including sensor) new belt radiator 1new freeze plug(the second one is coming cant get to it yet leaking slowly) all this was done while still driving the car i bought it for 300 and wasnt planning to fix it just a-b it till it dies second car died so here i am please help

Welcome to AF. Check the fuel pressure, if ok, try disconnecting the maf and see what happens.