I have a 2001 Mustang GT. Here is a brief history in case any of this sparks a thought with somebody. The car ran great most of the time ( 2 yrs ago). The car would sometimes start hard and run very poorly (lots of misfires and would not hold an idle) if it had rained or was raining. High humidity (in Florida) seemed to be a factor as opposed to something actually getting wet. After the car warmed up, the car would immediately run fine. I am assuming the computer switched to closed loop and the O2 sensor kicked in. Then I moved to Texas (no humidity) and drove the car for a year without a problem. About a year ago, the intake manifold cracked at the thermostat housing but didn't have time to replace it. So the car sat for about a year. Fast forward to 2 weeks ago. I replaced the intake manifold and charged the battery. The car started hard and ran very rough as it did on high humid days in Florida. But even after the car warmed up, it would not run better. I let the car sit for a couple of weeks, recharged the battery again, and purchased an OBDII device. Now. I put the OBDII on the car and kept the car running until the car warmed up and the closed loop condition started. After a few minutes it ran pretty good, but would not hold an idle unless I helped a bit with the gas pedal. The car eventually stalled. When I restarted the car, it ran very poorly again. It would run slightly better in the closed loop condition, but it still ran very poorly. It sounded like half of the cylinders were not firing. Eventually the car stalled at low rpms and now the car will not start. The engine turns over but will not fire. If I touch the gas pedal, the pistons spurt a bit like they are trying to fire and the rpms kick up just a touch, but that's about it. When the car was running in closed loop, the O2 sensors on one side were fluctuating wildly between 0.1 and 0.9 V. The other side seemed rather stable (I don't recall the voltage but I think it was mostly at 0.9V on the pre sensor and lower on the post sensor). Unfortunately I did not get any other information before the car died. When I try to start the car now, the first set of fuel trims (presumably short term memory?) fluctuate between 30-50% while trying to start the car and the second set of fuel trims are set at 99% (presumably long term memory?). The MAF is set at 3 g/s and goes up to 5 g/s or so when cranking the car. The fuel pump reads around 15 when cranking and drops to zero when I touch the gas pedal. The Timing Advance is at 10 degrees. Because the battery was dead I don't have any error codes from past days. And the current starting and stopping hasn't generated any error codes. I don't get why the fuel trim would be so high. Is my computer screwed up and running the car too rich to start? I am assuming at this point that either the computer is screwed up or I blew something that is preventing a spark or the injectors from working properly. Any thoughts on where to go from here?