surging

At the end of my rope, this is the last ditch effort before I haul it to the dealer! 1994 FZJ80. This issue only occurs when the vehicle has sat for more than about 30 minutes. Upon cranking- very rough idle. Then when driving, slow acceleration, low power, surging, etc. Then, all of a sudden...

Ol' girl has about 310K on the odometer and she is behaving in an abby-normal manner. Recently, when cold, and the engine is at high idle so to speak, and I wait for her to settle down to a normal idle, once that happens I shift from Park to Drive. Once I do that the RPM surges to and the truck...

Title pretty much says it all, truck is 89 22RE. Thanks for any input. Ray