Please help mkIII weird problems

[Bru]

Just as a shot in the dark, try unplugging the brake light failure module which is located near the rear hatch latch behind the plastic cover that goes from one side to the other. The module on the drivers side. Water tends to get into it and cause problems. I fixed mine and put it inside a plastic bag so water couldn't get in again. Check your ground wires for the battery and the bundle of harness wires that attaches under the intake manifold. I left it hand tight once and it acted weird until i tightened it down.