Hey guys!

I have a 1990 3.0 4x4. Stock.

I immediately took it to shop and had the following done,
Oil Change
Steering Fluid flush
Valve Gasket Seal
Coolant flushed
New battery


I took it up to Yosemite area for a weekend trail trip, just before we hit the mountains we stopped to get food, it seemed to struggle at low RPMs and when I went to roll into the parking spot it died. Like, stalled. It was wiling to fire back up but wouldn't idle without stalling. We let it cool for about an hour then headed for the mountains. The first hill we made it to the A/T OIL TEMP light came on. Luckily we happened upon Chinese Camp which had a beer garden and little shop. Upon further inspection the trans was down a quart of oil. We topped it off and headed on our way. We almost made it up the steep grade until the light came on again. We stopped for gas and it continued to stall at low RPMs, when I opened the gas cap it let out a loooooong release of pressure. We made it the rest of the way to camp, and I did about 115 miles of trail driving the next day and did ok until the steep grade to get back to camp when the A/T OIL TEMP light came back on as I neared the summit. Luckily the rest was downhill so I coasted my way down and 10 minutes later it went off.

After the trip I took it to a Drivetrane shop and installed an external trans cooler and flushed and replaced the Trans oil. I take it out the following weekend to go to Bowman lake and I don't make it 30 mi on I-680N before the trans overheated again! It seemed to lose all power on the hills, i just kept losing speed. I took it back to the shop that installed to cooler and he was stumped and recommended i replace the water pump and thermostat. I did the thermostat but the old one looked brand new.

Does anyone have any insight?

I know there is a minor leak in the rear main seal and there is a light ticking in the engine area which no one has stated to be of major concern.

The head gaskets were done about 4k miles ago, along with a standard tune up.

Does not sound good. The external cooler should have been the solution. Maybe your torque converter is bad? They generate a lot of heat.

Thanks! You're the second person to suggest that. I found a new shop that has come highly recommended for trans so we will see what they say!