hello, I have a 1999 dodge ram 1500 and the transmission is not upshifting from 2nd to 3rd and the rpm's are around 2000 to 3000 between 20mph to 30 mph.. I've already changed the fluid and filter the bottom of the pan had some gummy substance around the magnet and the fluid was a dark purple color. There was only very small particles witch looked normal. This all started last year when the temp gauge for the trans appeared on the dash then it started to slip alittle........I've had a trans shop tell me it needs a rebuilt but thats alot of $ .. So im thinking small like the Governor valve or some silinoid or the torque converter... Was thinking of using some trans seafoam to see if it worked..

 

Are you scanning the truck for any codes?