Background: Original owner purchase. Promptly had the trans rebuilt and bullet proofed. EX is an 03, Edie version, 2wd. It has 156k on it, now has 178. I use it to tow my travel trailer back and forth from Cal to Kansas and to tow a car carrier. IAC, TPS have been replaced. But not the crank sensor. It starts, runs sweet then when warm....

Vehicle keeps tossing misfires. I've replaced plugs. I put chino cheapo Ebay coil packs in, they lasted about a month. Misfires again. Usually a 302 or 306. Sometimes its fine for hours, then at a stopsign idling, or hooking up a trailer, it drops a cylinder. Rev it up, idles nice, then drops again. At a stop sign you can feel it come and go.

I bought Blue Steaks from RockAuto. These were used to replace the chinos. The misfire comes and goes.

I was told to order Motorcraft NEW. At $35 each I did. Almost $400. The possibility of an injector? At 178k yes. I did have an issue last week coming out of Kansas on I-40 through NW. It was 6 deg outside, we were running along at 70 towing, when the cruize shut down. When I reacted. and shut the cruise off, it would buck and stumble but run. I limped into Flagstaff. At the Ford dealer, who could not work on it, (it would not idle at all) when the Service Manager went with me to peek at the unit, it idled! He said load the hell out of it with HEET and head home. It ran fine. Misfires come and go.

The cat was stolen. It now has straight pipe. I do have the 02 behind the cat that tosses a 420 once every 300 miles. Clear it. 300 later.... that is where i picked up the misfire codes. Pending, no CEL.

SOOOO

One more time, toss the Blue Streaks, put in Motorcraft when they arrive this week. BUT---Bosch sells an upgraded injector set (10) for $350-- FoMoCo are $600. I really like this EX. While my 99 Suburban with a Vortex that has a stage 1 cam, and upgrades at .30 over, will outpull the V-10 all day long, I like the heavy feel of this EX. And with 4 dogs when we go camping and traveling the back is perfect for them to lounge around in all day long.

I loose no coolant. I use no oil. It runs sweet when it runs. But you can feel and hear the misfire that comes and goes.

Am I on the right track? We can find no vacuum leaks. And yes, I have dumped a **** load of chemicals down that snout in the back trying to clean up the injectors, if one or two are dirty. BTW the fuel pump was replaced by Ford in Liberal, Kansas in Aug. Factory with a new filter. If I have a dirty injector I cannot clear it. Or at least not using the plethora of chemicals from Lucas, to Tecron to Seafoam. I try to run Costco fuel. But on the road I am at the mercy of Indian Casinos on I-40. I prefer Loves or FlyingJ. Fresh fuel.

Whatever occurred coming into Flagstaff last week could have been moisture in the tank, the wind chill at 70 might have froze some of the water that could have been picked up at the last fuel stop.