1999 Mustang Electrical Failure

Hey I am new to the forum. I recently purchased this 99 Mustang (65K original miles) and it has been running pretty good until I swapped out the headlights. The previous owner had led's and the lenses were all crapped up, so I replaced them with the Halo-LED with the standard bulb. I am not sure if this is what is causing the issue but while driving the fuel cut off at idle and I thought it was a fuel pump. Mechanic said Fuel pump was fine.

Two days later I get in the car, completely dead. I jump start it and drive a couple of miles and I lose fuel to the engine again. Luckily it started again but a few miles later ALL power shut down while driving. No hazards, nothing! I jiggled the positive terminal and it started again. Definitely an electrical issue, not sure if the new bulbs are causing a draw issue with some kind of relay (I am not an electric guy).

Has anybody ever experienced this? Also could a dead battery in the key fob cause this (causing the factory alarm to engage)? I brought the car back to the shop and then realized this and put fresh batteries in the fob and left it with him. I would really hope this is the issue, but I would rather explore every option than get stuck in the middle of a highway again.

Thanks! Any helpful replies would be great.

Thank you! I believe that was precisely the issue. That screw was stripped to the point that it wasn’t tightening. In order to get it home I wedged a penny to tighten the connection. The lights are not flickering like they were.

That was one of three things I did. I also swapped out the battery in the key fob and had a loose positive battery terminal. I would like to take it for a long cruise with fingers crossed.

Thanks again. Electric issues can be very intimidating