I have a 1997 road king that started with an occasional stumble to a back fire once about 15-20 miles to a 15-20 second misfire. This all started on the way back from Sturgis. Symptoms are when I fill up it seems to run good for about 20-35 miles then will start misfiring and will get much worse as miles driven but when starting to misfire acceleration will clear out and run ok for a mile or two and then back at it, seems to run fine under a load or accelerating or at 80 mph unless going downhill at a coast will miss when running at slower speeds under 60 mph it is a constant hit and miss and when I got into the Phoenix valley when the heat got really high the miss intensified will also act up in a long sweeping right hand curve and when on a rough road or harsh bump will trigger miss, when it stumbles the tack will drop about 2-500 rpms but will not act like it does when the kill switch is activated . I spent a lot of time looking for a shorts I have a power commander that I disconnected and had driven about 450 miles with no change. Would the most likely be the ECM, tps, or fuel system oh yes no engine light would come on! Any ideas?

 

Start out by pulling a plug out and see if it black and overfueled, possible temperature sensor failure and overfueling, I can't see an electrical failure fixing itself on a hard pull while running hard.
Your engine can use the extra fuel while accelerating hard or high speeds and be flooding the cylinders lower speeds and the eng temp sensor won't always throw a code. Won't cost anything to pull a plug.

 

Thanks for that idea Bagger now that you mention it I did lose about 18 miles per gallon and sadly enough I had a new temp sensor with me on the trip that I didn’t try, I’ll install that and go from there and yes the plug had a indication of fouling on the lower area of the electrode but very clean and white at the tips, kind of a weird pattern so I will be installing those too.

 

was the problem ever solved, and was the temp sensor the culprit.