I was driving home home from working out of town in my 98 Ram 2500 8.0 with 211k miles and after about 40 miles on the Interstate my truck started to buck and cruise control stoped working. I drove it some more and it started to buck again and again. The bucking was occurring at speeds of 75 and over, if I stayed under 75 the truck was just fine. I changed the TPS and cleaned the Throttle body and took it out again and again after 40 miles or so is started to buck again at 75 MPH. I am at a lose on what could be the issue, can any body help me out please.

 

Was the check engine light flashing?

 

No codes, I even ran my code reader just to be sure and there was nothing on the scanner. I wish it would have thrown a code to give me some ideas on the issue. From some of the resurch I have been doing it may be fuel related.

 

I was thinking misfire(s)

 

I'm thinking bad gas, bad fuel pump or filter. I was trying to find someone to give me any other ideas or let me know that I was on the right track.

 

You need a fuel pressure gauge (you can rent them at your local auto parts store) to see what the pressure is while idling and driving.

 

Yeah, first thing that comes to mind is inadequate fuel pressure. Next guess would be one of the coil packs is getting hot, and breaking down. One would think that would set some codes though..... But then, on my 8.0, I had a dead miss on one cylinder due to a burnt plug wire, and it never did set a code........

 

F.W.I.W., on my 8.0 I had a #10 spark plug die and it did set a code, and I really could not notice it driving any different.

 

Yeah, the V-10 is a smooth runnin' motor, even on nine cylinders...... Haven't decided if that's a good or bad thing yet.

 

crank shaft sensor. I had the same backfiring/misfiring at high speeds on my first ram when the shade tree dude doing my tranny swap broke the crank shaft sensor and replaced it with the wrong one.