1988 Ford F-150 4.9 liter 6 cyl. 5 speed manual trans. During the winter I noticed the engine was running rough for a while and then the ignition module failed and I replaced it. Now that the weather has warmed up it has started to run rough again. When I first start it up it seems to be running smoothly, but within the first one half mile it starts to miss and jerk. I have changet the throttle position sensor, but no help. There are several inputs to the EEC that are tempeture sensitive. Which should I suspect?
Well, I think I found it myself. Suspecting the engine coolant sensor, I disconnected it. Then started the engine. The engine now would definately not rev up when I step down on it. Plugged the ECS back in and after a warm up gave it the goose test. Seems to run fine now. Manufactures NOTE The EEC should have a manual reset.