Stumped
 

I have a 98 Trooper, with around 130k miles on it. It has done great both on road and off road, hardly ever any problems. Last night I came across a problem which neither I nor anyone else could figure out.
For the past week or so, when I start the car it sounded like the starter had a hard time turning over, or it had to work real hard. This problem would happen, then not happen, unrelated to time of day or how long the previous trip was. Then last night I went out to start my car, the engine turned over a few times, where it sounded like it was working really really hard, then died. I thought it was the battery so I pulled out my charger and hooked it up. The battery was reading full. I took it down to Autozone and they tested it, no dead cells, and full charge.
After talking to a few people and reading others posts on the internet I swapped my starter. But still have the same problems. I tried a fresh battery in the car just in case, inspected my cables, and anything else I could think of.
When I try to start it, all the lights come on full strength, the door locks work and everything seems fine. When I try to start it, everything goes dead and none of the lights or electrical stuff comes back on. After sitting for about 5 min, or resetting the battery the lights come back on as before.
Anyone have a clue? I am fully stumped.

you said you went off roading if so did you encounter water mud etc. so you said you inspected the cables, that said hou well did you inspect the first thing that came to my mind is maybe somewhere in your cable,could be anywhere if you have a small split or hole in the batterie it is possible over time moisture got inside and causing this problem....Check all cables very carefuly

also if you are still having this prob have someone try to start and play and wiggle the wires everywhere even the plugs at the firewall and fuse box

Double check both ends of both battery cables, and the other ground cables (body to engine, body to frame) for loose or corroded connections.

You might also borrow an OBD-II code reader and check for any error codes.