1990 Toyota Pickup no power and idles rough about 200 - 400

No power. Can just barely make 55 mph on highway and have to get there extending rpm in 3rd and 4th gear. Can floor the accelarator and not get any increase in rpm or speed and then seems to begin to lose speed. Slightly pull back on pedal and rpm and speed holds or returns to 55mph. No power to climb small incline.
changed fuel filter, spark plugs, spark plug wires, air cleaner. Gapped open flange at catalytic converter to ensure not plugged. Ran injector cleaner in fuel tank twice, poured sea foam in crankcase no change. Cannot find any leaking vacuum hoses.