Running Rough At Startup

I have gotten some ideas on what it could be but I just wanted to hear a few other people.

After the jeep has sat for 5-6 hours and a try to start it up it runs VERY VERY rough for a good 20-30 seconds. It would die but I rev it and hold the RPM at arround 2k for thouse 20-30 seconds then everything goes back to normal, no problems while driving it is just at start up after sitting for a while. I keep hearing it is a pressure loss and I can install a BMW check valve to "bandaid" it. Just wondering what anyone else thinks.

Thanks
Chris

Loss of fuel pressure due to a faulty anti-drainback valve could indeed be the cause of your problem though on '99-'01 models, there's a TSB relating to a faulty sealing ring on the fuel pump module causing the same problem.