2002 Ram 1500 Transmission problems-need help

About a month ago I noticed my tranny slipping a little when cruising at hwy speeds. I took it to my mechanic who changed the filter and fluid. He said there was no metal shavings in the pan and no burnt smell to the fluid. It ran good with occasional slippage for a few weeks. Occasionally the truck would shudder on the highway for a second, then be fine for a second, then repeat the cycle.

The other night it felt strange driving home. No slippage until I got to my driveway which is an uphill slope. Then it acted like it was in neutral. Even reverse didn't work. I backed it down to level ground, re-started it, put it in neutral for a few seconds, then put it in drive. It engaged and I was able to move, but as soon as it hit the hill....nothing.

I've read everything from it possibly being a pressure sensor to needing the computer reflashed. I'm hoping there's a solution that doesn't require a new transmission.

Any help would be appreciated.

You need to go to a transmission shop that has a transmission code reader. It won't trigger any light.