My 1996 cougar engine dies after it is put inreverse or drive but starts right up when it park. the battery gauge shows normal & i tested the alternator by running the engine and disconnecting the pos battery cable it still ran. the temp guage is normal. i stumped help

My 2001, a manual shift, had a similar problem. My mechanic found flaws in the wiring harness near the shifting lever. When the lever moved, it brushed the defective wiring against the frame and grounded it. All is better, now, after the wiring was replaced.