My friend wes just picked up a 91 4.0 sport for FREEE!!!! with under 100k on it! But i guess he found out the fuel tank had lots of rust in it and he made the mistake of fireing it up after its been sitten for over 2 years! Hes replaced most of the fuel system but the jeep just randomly dies... and sputters randomly. any idea whats up??

 

You probably wont get too many replies to this thread as the question is fairly broad and you there are far too many possibilities as to the culprit. If you could eliminate some of the major systems and compnents from the list of possibilities you might get a few more replies.

 

first off, test the pressure at the fuel rail.
if that's good, then check things like fuel filter, injectors, and even a plugged cat will give the same symptoms.

 

x2 on check Cat. Random sputtering and dying sounds like it's clogged up. Is the exhaust manifold in good shape?