trouble with my 95 dakota?

So without going into great detail Ill explain the issues Im having. I have a 95 dakota V6 A/T 4x4

1)I went camping this weekend and took the truck up some long hills. The thing will run fine then all of a sudden it starts to studder, my tach will drop to zero but the truck is still running. Or its will miss and start to diesel and I can hear like a back pop in the cat or exhaust

2) I can run the car to work on flat ground all day long no problems, but if I take it on a long run say 10 miles when I brake and turn to stop somewhere the car dies, same thing lately too even on short trips it will idle like it wants to die, But if it dies and I restart it sometimes it will run fine for a week after that, like it resets the CMU or something. One last thing I noticed it I when I go on bumpy roads the tach jumps all over the place and the truck will die then run die then run.

I have a mechanic who we take our fleet to and he said something to the effect of it being something in the belthousing but im not sure.

Dont know if it makes a difference but gas guage is one of those that reads empty when its full and half when its empty.

My 3 thoughts were fuel pump is going, loose wire/ ground or my cats screwed up or plugged.

Any help or ideas im very good with cars but this one has me scratching my head, Thanks

If I need to explain more leave me your email or something