Intermittent hard stumble and sometimes dies

[Bigredwelder]

Well, I've searched and found similar issues, but nothing that really matches. I have a few thoughts as to what this is being caused by, but am asking for input from the experts!

First time this happened I was cruising at about 70mph, and I felt three separate, hard quick stumbles, that stopped just as fast as they happened, that were just a split second long, while driving from Dallas to Colorado Springs. Each one of them was separated by over a hundred miles. This was a week ago and had no reoccurrences until yesterday. This time it happened in stop and go driving twice. The first time is continued to stumble almost until the point of dying. The second time it stumbled so hard it killed the engine. After I was able to roll into a parking lot, I shut the key off and back on. It immediately re-started and has shown no symptoms since ( approx. 60 miles).

The engine is mostly stock, 4" exhaust, a mild chip (I am told, I have not had a chance to see what kind it is), and a mandrel bent down pipe.

Any thoughts?

[Bigredwelder]

To add to the above info, I am also experiencing an extremely hard start issue when not plugged in overnight. If I don't plug it in overnight in less than 40 degree farenheight temps, it will not start.

I'm thinking the two may be related, as I have checked the GPRS and it tests fine, so that leads me to think the under valve cover harness may be going bad. The only thing that doesn't add up with this theory, is that when the engine stumbles, it's not like its dropping a cylinder or two, it feels like the whole engine "hickups", for lack of a better word.