I just rebuilt it and had it running and doing fine tuning on it. It a '94' 3ltr V6 by the way. So today I was gonna like it run alot longer than I usually do to fully seat the rings. It starts up and runs fine for a 1 or 2 minutes then it sputters and shut off. I start it back up and a sputters and shuts off. If I wait 5 mins and leave the fuel pump on it'll start up run 1-2 mins and do the same thing. I changed fuel pumps and fuel filters and it does the same thing. What am I doing wrong you guys?