Mike came by Saturday and we looked some more at my random misfire with my jeep

I *think the cause has something to do with my evap/vacuum system with my fuel. The reason for this is I have replaced nearly everything under the hood, new plugs, new coil rail, new throttle position sensor, new crank sensor, new cam sensor

I can clear the code and drive around for awhile without it coming back. However if I clear the code drive around, then take off and put on my gas cap, the code will come up once I reach 70mph on the freeway. (codes p0300, p0301 through p0306... Basically every cylinder misfires)

I thought that if my fuel mixture was off it would cause an improper mix in the injectors causing them to misfire. Thats why we were checking for evap leaks and also why the codes come up once I release the pressure in the system by removing my gas cap. (at least thats my theory)

We dropped the tank again and made sure no hoses were cracked in the evap lines and checked under the hood to see if we could find any leaks. We couldnt find anything

Im really running out of ideas. Any wild guesses or thoughts?

maybe something good will come of this? A guy on the VJC is having the exact same problems Im having

http://www.virtualjeepclub.com/showthread.php?p=428766&posted=1#post428766

Hmmm, I wonder if it's "over pressurizing" the fuel system for some reason? Have you checked what the fuel pressure is at the rail?

Other than that it might be worth a few bucks for you to take it somewhere and have them put it on their scanner that can tell you more than just OBD-II Codes.

I have an OBD II reader that also monitors while you drive. You are welcome to borrow it.