this maybe be real dumb, but have you checked fluid levels? i'm sure you have, but in my own idiocy
![Hammer Head :hammerhead:](https://board.marlincrawler.com/Smileys/marlin/hammerhead.gif)
i was having similar problems, plus it was idling rough and i never checked the radiator fluid. turns out a hose was loose and it leaked enough to effect idling...
![Doh! :doh:](https://board.marlincrawler.com/Smileys/marlin/doh.gif)