i had a similar problem with mine it turned out to be the pick - up in the distributor getting hot.mine you would have to wait ten minutes or so then it would crank and run for 5-10 minutes then die like you cut the key off. the module could be getting hot also. years ago autozone checked a module on mine and said it was good but you drive it down the road and it would die and give it 5 minutes or so and it would crank up and run a little more and die again. i just spent the $15.00 for a new module and it was fixed . you might check e-bay out for a code reader for a '93 ford. i have one for an '88 but don't know if it will work on a '93.i think i gave $18.00 for it years ago.it will work on my '85 also.it plugs in the diagnostic plug on the fender and beeps the code.some of the models you have to pull the distributor to put the pick-up in the distributor.advanced auto used to check codes free. i would just get the phone book out and call around and see if any parts stores can read a '93. most have updated to newer models but some still have old readers.you just have to find them.as far as the shoddy dealer turn them in to the bbb in your state.