Check each wire at the junction on the firewall.

Had one that would intermittently quit running. Drove me crazy for months. I finally had a buddy help me check each wire at the junction box on the firewall. He leaned over the fender, and I was under the dash. Together we pushed each wire in the junction box together. We found 3 that were not making full contact. If you bumped the harness just right, it lost connection, but if you bumped it just right it worked great.

You getting things working when you set the e brake triggered my experience. I'm betting setting the e brake is moving the wires to something that has a flakey connection.