I just bought an 2001 Cherokee sport for my sons first car. The guy I bought it from had a fuel pump put in and somehow botched it(the sock was in the bottom of the tank and gas leaked out the top when you went to fill it up. I had my(reputable)mechanic re-install fuel pump. I went to get it inspected and was told I needed to replace gas cap so they sold me a universal(this may not matter but I'm mentioning just in case.) Now when the vehicle has been running, it will act like its running out of gas, I can shut it off and restart it and it will run normal for a while, then act up again. Any ideas what could be causing this?

 

The tank could not be venting correctly. Did the behavior start when you changed the fuel cap or was it happening before the new cap?

 

Remove the gas cap and drive. Does the problem continue? Measure your fuel pressure while the issue is happening.