My 88's been touchy on starting for quite some time. Sometimes I hit the key and it cranks immediately. Other times I'have to hit it 4, 5, maybe even 10 times before it works. I did replace the ignition switch many years ago with a used one. Seemed like the trouble went away for a while, but came back. I've had 3 different starters on it, and just today changed the main relay over the ECU. I also thought it might've been a poor ground issue, but I added an extra ground cable to the block/battery a while back. When it's in the start position things click and hum, but no cranks. Suggestions?