95 4Runner--Rough idle, loss of power,
 

PLEASE HELP! Stumped and need advice. 95 4Runner 3.0--- Rough idle at speeds under 55. No power unless I take it out of overdrive and around 60 mph I can put it back into overdrive and it runs okay. Still skips but not as bad. Doesn't idle as rough in neutral but still skipping. When the outside temperatures are cool (early mornings--late nights) it runs alright. Has power and I don't have to take it out of overdrive. But the hotter the outside temperatures are the worst the truck runs. It acts like it's only running on five cylinders. It does have alot of blow back out of the valve cover on the driver's side. Everything on that side is soaked with oil. I've replaced cap, rotor, plugs, wires, cleaned maf, timing belt, water pump. Thxs