[BirdDog]

If it were me, I'd probably start by changing the ignition switch just to rule that out. A myriad of problems can arise if that is going bad...

Next I'd have a look at the waterproof immobilizer case under the drivers seat. I just installed one in my car last month, and although it wasn't a hard thing to install, the fact that the previous owner(s) changed the immobilizer means that those (large black and white) connectors also saw water. They could be corroded. If the connectors still had water in them when they were sealed inside the waterproof box, they could have continued to corrode after it was sealed up. Also, it's possible that whoever installed the waterproof case didn't do a good job sealing up the wiring harnesses. You really have to work the silicone adhesive into the wire bundles to get it to seal properly.

The top cover of the waterproof case is sealed with a bead of clear silicone sealer all the way around. It might not be the easiest thing to get off.

Hang in there - I'm sure you'll get it all sorted out!