2.7L starting issues

Hey everyone, new here, I'm looking for some help troubleshooting my truck.

I have a 96 Taco with the 2.7 and ever since I bought it it's had trouble starting. It sounds like the battery is dying when you start it (slow loping sound, kinda fades until it barely fires) but it usually starts. I thought it was a bad battery so I installed an upgraded battery and no luck. 6 months later it finally fails to start and I figure must be the starter. I change that and it'll start again but same old problem. I went ahead and changed battery connectors and have tried troubleshooting the IAT by starting it at various times with it plugged in or removed. Same thing every time. Any thoughts?

 

Bad ground between battery negative and chassis or chassis and engine block?

 

It's got a weird wiring setup. Looks like someone was Jerry rigging a fix and it has an extra ground coming off the battery to the body. That might be it.

 

This should be a picture of the extra ground

 

That work is a piece of art. Belongs to museum, not a running vehicle.

 

quick and dirty way is to have someone try starting it and you grab the wires one at a time from the battery to the engine ground, battery to the starter etc. Be prepared to let go quickly as they might get superheated... if they do, that is a bad wire and/or connection... the official way is to do a voltage drop test.