1988 rs turbo running 16psi, about 160bhp.

First one, is there a certain gap on the plugs, I set them to .8 and it started to miss under boost, same at .6 but okay at .25, using ngk r.

Setup at the rolling at nobles, car was running mint, but recently when it gets to 4 and a half rpm it sometimes holds bk, any ideas what this is. something to do with plugs??

When u press the windows, or the brake peddle, the rev counter jumps, any ideas what this is?????? when the light are on the battery light comes on faintly, or the more power u use the brighter it gets, but its still charging well, as I have a volt meter on it. Any help well appreciated. Thanks.