98 Bravada Transmission

Every once in a while, my 98 bravada acts weird while driving. it only happens after i've driven about 20 miles and it only happens once every couple weeks. the transmission will start to shift very harsh. when i accelerate from a stop, it will spin the tires a little when it goes into second gear. the other shifts are also harsh. it will then throw an engine light which is: "transmission component slipping". i'll reset the light and the next day it's fine again. i also noticed when i bought it that when i shift from park into drive there is a delay. i recently changed the trans filter and fluid. the truck has 98000 miles and everything is still original. are these problems related?

The '97 manual says:
HARSH SHIFTS
Open or shorted circuits with the TPS,Vehicle Speed Sensor, Trans. Fluid Temperature Sensor or Engine Coolant Temperature Sensor.
Also, contamination or damage to pins with the Pressure Switch Assembly or pressure control solenoid.

I have a 98 also had hard 1-2 shifts..I changed Fluid & filter and added lucus atf fix now it works like it should..also it cured torque converter problem. ( kept slipping in and out at highway speeds) hope this will help