The engine would stop when speed is reduced or stopped.

Crankshaft position sensor problem .What engine ? 3.1 , 3.4 , 3.8 L

check fuel lines and filters , filter could be in tank .

Sounds like your fan belt is glazed or loose. At higher speeds the belt slips over waterpump and doesn't drive pump fast enough to circulate coolant. That would be first thing I would check...
Other possibilities: waterpump, blocked heater core, fan clutch.

p0430 is the code for below normal catalytic converter efficiency. This may mean that the sensors are faulty in your exhaust stream or that the catalytic converter is clogged or otherwise damaged. That would may also be the reason for the rough idle. Clearing the code does not repair the problem. When codes are "cleared" it simply wipes your code memory clean until the onboard computer has a chance to re-establish the condition of your overall system. This cycle may take several days to weeks depending on how far and how often you drive. Usually there is a sequence of events that have to occur such as acceleration above a certain speed than a stop then a steady speed trip of several miles then another stop. Your engine has to reach normal operating temperatures as well. In short the code will continue to return until you track down the problem.

dealer only the software for this gearbox is encrypted so only a dealer can plug into it to diagnose

Electrical probblems are always the hardest to solve. I don't believe it to be the ecu, because when one fries it doesn't work at all but that may be the case. I believe from what you describe there is a short somewhere between an important censor and the ecu, like mas, 02 or throttle positioning censors. Ive also come across cases of which the catalytic converter was clogged making the car not operate correctly. Hope this helps.

Gauge light illuminates when the ignition is switched on. It should extinguish as soon as the engine starts.
If it illuminates with the engine running, it indicates a malfunction with the engine management system. Have this checked as soon as possible.
If it flashes when driving, reduce the vehicle speed immediately until the light illuminates constantly. If it continues to flash, avoid heavy acceleration and high engine speed, stop the vehicle and have it checked immediately.
On some vehicles this light may be red – again stop the vehicle and seek assistance.
If it is safe to do so, try stopping the vehicle, switching off the engine, wait two minutes, then restarting the engine to reset the engine management system.
With the light illuminated, the vehicle is still safe to drive as long as no other faults are apparent with the engine. Have the vehicle checked by a dealer or garage as soon as possible to avoid any damage being caused to the catalytic converter.

bad torque convertor solenoid , unplug the electric connector on transmission u can drive your car fine and save yourself a $1000 repair

sound like transmission slipping .fuel filter clogged.turbo stop woking.dirty fuel injectors.

If its the 3.0 diesel it could be the rail oil pressure sensor starting to pack up .