Loss of Speed Control

By "the sensor on the brake", do you mean the pressure switch on the brake master cylinder? If not, check that, assuming you have it. There was a huge recall on many of them, involving the installation of an inline fuse to prevent fires should they corrode and fail (as they were on an always-hot circuit), so check that inline fuse too if you have it...and enquire about the recall if you don't. I'm not sure if '91 is included in the recall or not; I do know my '98 was and has the modified wiring harness.