Hey guys! Friday night I got a CEL and started noticing some issues with my transmission while driving and shifting into reverse or drive.

I checked the CEL and the ONLY code I get is P0700, there are no associated codes.

There are a couple issues I am able to notice. The first is when I shift into drive or reverse it kinda 'slams' into gear. It kinda jerks the car and its a loud 'thunk'
Second is it doesn't seem to want to go into 4th gear. Driving at 60 mph I am up over 3000 rpms.

I am thinking it is a shift solenoid, but talking to a couple guys they were saying it sounds like the torque converter. I don't have any experience with auto trans maintenance and trouble shooting other than occasionally changing the fluid and filter, so any help is appreciated!