I have a 99 24 valve automatic 4x4. My heater grid in the intake is not working. Also my transmission is constantly jumping in and out of overdrive at 45-60 miles per hour. Any help appreciated thanks

 

The lockup problem is really common. There are a million fixes on here including tinfoil on the alternator wires. I fixed mine with an inline filter for the lockup signal, Geno's has it fairly cheap.
As for the heater grid first thing to do is trace power. Do you have power to the grid? To the solenoid? To troubleshoot you need to start at the easiest. How about the fuse?

 

I have power to the relays but they are not getting activated. The relays do work I jumped them with a hot wire from the battery to check them