Transmission problems on my 00 dodge avenger

[Anthany]

The tranny shifts hard when shifting between gears, and when I'm at a stop light in drive with my foot on the brake the tranny makes a noise similar to a grinding noise and it vibrates through the whole car. Only happens when I'm in Drive and i am on the brake. Any ideas?

[KevinT]

I think these tranny's had a locking torque converter for better economy at highway speeds, my guess is that it's not unlocking properly.  First step would be checking the condition of the fluid, if the viscosity has gone off there's no telling what symptoms that will cause, and changing the fluid is the cheapest possible fix so it only makes sense to try it first...  Good luck!