I have recently rebuilt my 4l60e transmission in my 95 k1500 with the addition of a B&M HD shift kit. It has been working great for about 6 tanks of gas now and all of a sudden it shifts too soon. I really don't have any first gear and the other gears wont shift past 2000 RPM. It worked great till all of a sudden it did this during a few hour drive.... I can manually shift it till whenever i want and no problem but in 2nd,3rd,or OD it shifts too soon to the next gear.
I have had soooo many problems with this truck i reallllly hope i can get help!!
even just ideas are appreciated!

 

i also just ran fault codes and there were none other than my usual egr

 

UPDATE:
Ok so my blower fan has been on and off the last week as well. I would work for a few minutes and shut off. I realized if i shift into neutral and back it would come back on. It finally quit completely and i wiggled all the wires i could think of, checked all the fuses but called it a day since it was late. took it for a quick drive and it shifts normal again and the blower works too!!

Is it possible for these to be linked or is it just a coincidence...
If so where should i look?
Bad ground somewhere im guessing.
I was also going through a lot of mud and water prior to this happening so im thinking its external