Lull 1044C-54 intermittent rough running, sounds like running on 3 cyl

Hello all, I'm new to the forum. My older Lull telehandler has recently started acting up intermittently. The Cummins 4 cylinder has been starting to run really rough after the machine gets up to temp. If I shut it down and let it sit for even 5 minutes, it will sometimes run better for 5-10 min. I drained fuel, refilled with new fuel (no water to speak of and old fuel seemed fine) then replaced inline and main fuel filters. After doing this it ran much better for a few hours, then went...

Lull 1044C-54 intermittent rough running, sounds like running on 3 cyl

Lull 1044C-54 intermittent rough running, sounds like running on 3 cyl