Hey I'm brand new to the forum but have been searching around and found lots of useful info so far! I just bought my first Jeep last week, its a 96 XJ with 4.0 High Output, and manual tranny. It's got 171000 miles on it. When I bought it, it didn't seem to have any problems, but now its started randomly jerking and losing power. There doesn't seem to be any pattern to when it happens either. When I'm going highway speeds and it happens, it will kinda buck or jerk and sometimes it loses power and starts to slow down, but doesn't last more then 3-4 seconds. It also sometimes does it as I'm accelerating. For several days it would do this and not die. I thought it might be the fuel filter so I replaced that today and it didn't seem to help at all.
Then today, I was sitting at a stop light and it did it then it died. It started right back up then died again after a few seconds. It started right back up and I was able to make it home fine. Other than these times, it runs great and idles just fine.
I've done a bunch of searching and it seems like it could be a bunch of things. From what I've seen I'm thinking it could be fuel pump, crankshaft position sensor, throttle position sensor, or O2 sensor... I don't know where to start to narrow it down, and don't have the money to just start throwing at parts without knowing what it is! Does anybody have ideas for what it could be and how to narrow it down? Thanks in advance!

Dan

 

if you have access to a fuel pressure gauge it would be a good idea to hook it up to the fuel rail and tape the gauge to the front windshield, do some hard accelerations and monitor the fuel pressure, it sounds like you have a weak fuel pump that is loosing its pressure. I was having similar issues with my fuel pump, once I replaced it I haven't had any issues since.