This might by a little off the mark, but check the wiring harness under the #3 carb. It gets pinched and subsequently worn then shorted, when it gets pinched between the coolant hose under the #3 carb and the bulkhead. My headlights, gauges, taillight flickered also then went out. MRsled directed me to the wiring harness under the engine right under the #3 carb. I found 2 broken wires and 5 others shorting to the frame. check-it out. The heated shield sounds like a coincidence. Just a thought. The wire issue was common on 98-99's.