I have a 1998 Mustang Cobra, during the first year I let it sit for a few months without starting the engine, when I tried to start the car, the engine cranked but did not start. The Ford mechanic got the car to start. Now years later, the same problem... I was wondering if I pulled the chip & then placed it back again, if it would correct the problem? Any help

That will not work. I would:

. Test all under hood and under dash fuses with a test light or multimeter.

. Remove and fully charge the battery. Most auto parts stores will do this for free.

. Verify that the Check Engine Light comes on and goes out, when the ignition switch is turned to ON. If not, the PCM may be bad or it may have a corroded ground.

. Check for codes.

. Consider replacing the Crankshaft Position Sensor and/or the Camshaft Position Sensor, if the problem persists.

It turns over but won't start?
Are you getting any spark?
Can you test for injector pulse?
Does the check engine light come and stay on when the key is on?