My car did the same thing could not find the problem took us several trips and hundreds of dollars then my cars dash started flashing all lights on and off on the dash like a strobe light it was the ignition switch there is a video on you tube videos posted about this that will show how to take off the dash and replace it several times I found myself going anywhere from 40mph to 60mph and the car shut off on me it no longer does this and the dash lights work fine.
it needs a new throttle positioning sensor
I would check your Ignition Module. That's the first place to look.
Have vehicle scanned to see if any codes are stored to determine the problem
Because it's old
Why engine stalls on 1993 Chrysler Intrepid while driving and sometimes at stops?
Check Battery connections are clean and tight. If they are OK, then the problem lies in the relay mounted in the starter (it is one unit)
sometimes, but not while driving
One common cause is a leaking fuel pressure regulator. When they leak, raw fuel gets into its vacuum line and causes a rich condition which can cause the car to stall, and also give a hard starting condition. - TechJK --------------------------------
Fuel pump failure is one possibility.
Over 20 psi at idleUnder 80 psi while driving Over 20 psi at idleUnder 80 psi while driving
Check for spark & fuel when it's dead and go from there.
sometimes