Toyota Repair: 1997 4-runner 3.4LSR5, scantool, trouble code

Question
97 4-Runner 160,000 miles.I can put the accelerator to the floor and it will take a few seconds for the rpm's to increase. ( the engine just bog's down).In park it is a little more responsive however it will still hesitate. When the engine's rpm's come up and the vehicle is accelerating,there is a little more response but not much. on the highway the vehicle struggles to find a gear it can run in. so much so that at 65mph on the highway and going up a slight incline, the transmission will down shift and struggle to maintain 55mph.  

Answer
With all of this going on there should be a check engine light on, is this the case?  If not you should still have a diagnostic scantool connected to see if there are any pending or history trouble codes, it is not possible for this engine to have these problems without setting a trouble code or turning the engine light on.