(91000 original miles no bull) I am waiting on a scanner to see if it will help me. Not getting any codes. The beast runs fine until it approaches running temperature then starts to deteriorate until a stall occurs. Over winter it ran fine unless I took a long trip but the cooler weather helped reduce the symptoms. It doesn't get hot according to the idiot gauge. I was told to replace the cooling temperature sensor attached to the thermostat housing because it some how affected computer adjustments. That didn't work. I checked all ignition wiring and related parts and all check fine. I do notice it starts to run a little lean and the fumes seem heavy. The engine will seem like it's missing cylinders and back fire a bit. There is no smoking related to this problem. MAF replaced and ran sea foam through the system. Removed and replaced Plenum for valve cover gaskets and it looked like the seafoam did a good job. (FYI) I highly recommend ithe sea foam when your power plant gets to running sluggish. I was thinkin CAT converter but I don't know how to check it. This problem started last summer and it ran okay during winter but I have to get to the bottom of this. I have an F150 Supercrew as a primary vehicle so I have patients to spare. I'm a Ford man all the way.