Our 2000 dodge caravan failed to start with cold engine (3.3L). Started next day and drove fine for three or four starts. Next day it was dead again. Cranks over fine. New battery. Replaced cam position sensor due to breaking tab while removing to inspect. 55-60 psi fuel pressure at the rail. Tried new crank sensor. Primary and secondary coil circuit checks good per Haynes manual. No check engine light. No spark from plugs. No power at connector to coil pack. Mechanic suggested it was the ECM after looking at it. He found a used ECM and told me where I could get it and then said I would have to have it programmed with VIN. Put it in and it started up and ran pretty good, just slightly erratic idle at times but dealer said they can't program a used ECM. It ran fine for a few days then died just as I started pressing gas after stopping at light. Started up again fine, ran for several days then repeated again at a stop. Ran fine for a few more days then died at another stop and would not start again. Replaced ECM again with a programmed rebuilt ECM. No start. looked everything over again and found the plug for the upstream o2 sensor melted partly from touching EGR tube. Broke connector apart to check for short. Engine started and ran for a couple minutes then died and would not start again. Not sure if this was coincidental timing or something with the harness? Shouldn't it start fine with out the 02 sensor? Any ideas or suggestions?