2004 Chrysler Pacifica locking into limp-home mode

My 2004 (118K miles) Chrysler Pacifica is locking into limp home mode when I accelerate away from a standing start, unless I pull away very very slowly. It reverts to normal on stopping and starting the engine. Engine code is P7000. Some people have suggested its the speed sensors on the transmission. Would love to get some views and also opinions on how easy they are to fix.

Thank you

PCM fault P0700 indicates faults are detected/stored in the Transmission Control Module. You must access the TCM to retrieve more specific fault codes.