Transmission wont shift.last night it would only go 30 mile an hour.at one point it shut itself off while driving.

Take it back the the transmission shop, it needs to be further diagnosed and probably rebuilt.

Sometimes you can only diagnose a faultwhen it is their / happening ....try earth straps around engine remove , clean and refit

change the coded solenoid and the reset the ECM and after a few days read the fault codes again

There must have been a 'Check Engine' Light? When a 'check engine light' (MIL=Malfunction Indicator Lamp) is turned on, there is a DTC (Diagnostic Trouble Code) set/stored in the ECM/PCM (Engine Control Module/Powertrain Control Module). This code identifies which engine management system component/function experienced a malfunction. Once you pull/read this code, you may begin diagnosis. You'll need an OBDII (On-Board Diagnostics II) code reader. You should find a P07?? number stored (P07??... is a transmission code).

frozen, no. the computer did see a problem though, the transmission was put in what is called limp home mode, basically 2nd gear. there is a code that would of set in the transmission computer. have the code pulled and then post the code. more then likely a sensor is going bad.

run the fault codes to find the reported fault
engine lights report on engines and transmissions
could be actuator or vacuum to actuator, dirty transmission oil or pump pressure problems

Something is wrong with the torque convertor and or transmission. Make sure your trans fluid level is full.

MAKE SURE YOUR ENGINE IS WELL TUNED. MAKE SURE TURBO IS WORKING NO RESTRICTED EXHAUST..ALL PLUGS AND WIRES ARE GOOD.SOUND LIKE TRANSMISSION SLIPPING.HAVE TRANSMISSION PRESSURE TESTED.IF FLUID LEVEL GOOD AND TRANSMISSION FILTER NOT STOPPED UP.PROBLEM COULD BE TRANSMISSION SHIFT VALVES OR TRANSMISSION PUMP OUT PUT PRESSURE TOO LOW.

Check the U-joints at the transfer case.

Solenoids usually set a code that can be checked with a code reader.
Make sure that the oil in your transmission is full and clean...solenoids can get gummed up by varnish if trans is not serviced properly.