Engine quits Eninge stops running when drivng a highway speeds (above 45mph) this is random occurance. After the engine stops I can restart the car with no problmes and continue on.?

Radiator cooling fans not working? The ECM is protecting the engine by shutting it down.

Might help, disconnect negative terminal from battery for 10 minutes, if the compute is getting weird readings this will reset it and maybe help.

overdrive is for highway driving, lowers your engine rpm's and saves gas-allows the engine to not work as hard at higher speeds. Not desirable in around town traffic, and if you can lock it out if you do most driving under 45mph, a good idea so you don't 'lug' your engine.

I would start with plug wires rubbing on something and created a short.and is not compleatly worn through. a cheep place to start. good luck with it.

Take the car to camry automobile shop for the servicing of the car.

sounds like you have a bad fuel pump.Or possibly a clogged fuel filter.

My dad had the same problem with his truck, if you wiggle the harness that goes into the ecm(computer on the right firewall) it should start back up. If it does then your probably gonna have to replace the ecm

On an older engine, it is quite possible that the engine is just worn out. Check the compression not only for variation between cylinders but for lower than normal across the board.... should not be much lower than 120 in each cylinder. There is no timing adjustment on your engine so you pretty much are stuck with what you have unless you saw off the distributor hold down tab and use another means to lock it down and adjust it. You also need to make sure that the overdrive is releasing under load (when driving above 45mph, touch the brake and it should disengage momentarily). I'd also make sure that any "kickdown" cable or linkage from the throttle to the transmission is adjusted and working properly.
If the engine is otherwise running well, these items may help a bit. Make sure the air filter is clean and that the exhaust is flowing well. Without either the engine cannot breathe and will also have problems.
good luck

This might be the mass air flow sensor or egr valve.

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