At the firewall, remove the plastic cover for the main battery fuse. That terminal may also be oxidized, causing an intermittent connection to the battery.

 

Yes the post are cleaned and terminals tightened to them. The part at the firewall is also tight and premuch cleaned now. Today when I put the key in the on position to let the pump prime and gauges set, after five seconds it all shut off. I tried it again and sure enough after five seconds it all goes blank again and won't crank. Got out with my wrench took took off neg cable and tried it, wouldnt go. I unplugged pos and neg and put them back on. Started right up. Could it be an ignition switch?