Once again, this is stupid, but check the fuse panel. Don't know what '91 has for fuse set-up, but 84-87 fuses can be mistaken for a "spare" fuse. The ones along the side.... This is from experience. A 86 5k. Bought for $500.00 because it wouldn't run. Put in a new fuse and ran like a top. Rex Pedersen 85 5ks 86 5ks wagon 87 5ksQ 90 V8q