I have put a 5.0 HO into my 88 bronco II.....When I started the truck after about 60-90 seconds it would run really rough(whether at idle or driving) and pop back through the intake if you do anything more then grandma accelerate, felt like a HUGE loss of power and hesitating, it would run perfect after doing this for 30-60 seconds and wouldn't do it again until I shut it off, and then started it back up. So I thought I installed the 02 wires in the wrong order (right/left) to the computer so I switched the 2 pins.......and it stopped doing that weird thing after starting it up. BUT then it started doing something diferent, after warming up it would hesitate and miss while accellerating at anymore then grandma pedaling. if you slowly eased into the throttle it would have the feeling of the engine missing or this jerky feeling. I switched the 02 wires back so i'm back to it running weird for just 30-60 seconds instead of all the time. The engine has 500 miles on it...my set up is speed density (88stang computer). WHAT would cause this? new sensors include: 02 sensors, ECT, ACT, tps IS correct (about .98ish), i'm pretty sure that popping w/ the way i currently have the 02 sensors wired up is a lean pop but i'm not sure why that would be so consistant and go away like it does. fuel pressure is at 41ish w/ the vaccuum off, and 32psi at idle with the vaccuum on (stock FPR). pressure drops only 2 psi after 20 minutes of the truck being off. HELP!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!