97 olds 88-ls head & dash lights flicker

I have owned a 97 Delta 88 LS since 1999 and have experienced a problem with the electrical system about 18 month ago I thought I had it fixed when I found that when unplugging the red and the gray plug in to the alternator everything was ok so I seperated the wires from the harness and run them thru a seperate insulated protector and this worked good for a few months but now the problem is back. So far I have cleaned the ground on the driver and passenger under carpet they were like new no corrosion, I also cleaned the ground on the fender wall near the battery and he 2 grounds on the opposite side of car on fender wall. Would anyone have an additional idea, any help would be much appreciated. Thanks in advance

check around in the front bumper/hood area for grounds for the turn signal and headlights. also the trunk cargo area on side behind carpet.