[maxwedge]

Originally Posted by corning_d3

Hmm, it sounds like the coolant temp sender or the wiring is bad, which allows the engine to remain in open loop. The PCM uses a pre-programmed fuel table and doesn't rely on the oxygen sensor/'s while in open loop. I'd say your fuel mileage is horrible when this is happening, but as you said, it isn't doing it often. The ECT wiring is usually routed under the upper plenum, and for some reason it along with injector wires is well liked by rodents. It could also be pinched/chaffed. I'm not sure what the resistance of the ECT sensor should be, since it changes with temp, but I could check mine fully warmed and post back if you like..

Agreed, or an intermittent thermostat problem.