Need to figure out why my truck is acting up

[Bradley3054]

Came home from work and went to start my truck let the glow pigs warm up and fuel bowl fill, once I started the truck it ran like it was missin on one cylinder, had a little loop to it and wouldn't stop even after it warmed up and I rev a few times still doin it, so I shut the truck off and let the glow plugs warm up again and let the bowl fill and started it, ran normal like WTF. So went to town get some grocerys and went home and on the way home my service engine light started coming on every time I was coming to a hill and it'll drop to lower gear no more then 2k rpms and 5psi boost, like why is it coming home everything is reading normal and running normal. Usually it only comes on when I'm maxing it out with the chip Tony wildman chip but that's it, please help