Trouble shooting help needed for a tranny
 

I bought my first chevy a few days ago. Its a 1998 1500 with the turbo 6.5 L in it with the auto tranny, But i bought it not running got it running the ignition switch was fubar. Went to move it no forward gears. it does go to reverse but takes a long time to engage. Tranny fluid was dirty but not burnt so i changed it nothing stuck to the magnitic plug. Reverse is a little quicker at engaging but still no forward gears. I do have a clode reader but it does not seem to want to work for it. It is a dash daq scanner. Any tips would be appreacated before i go and put a new tranny in. thanks.

Any ideas? I just find it funny that reverse works but nothing else, if i leave it sit long enough in drive it will start to creep forward.