Power Flucuation 98 ranger

1998 Ranger, 2.5L,5 speed, 2wd, standard cab, 105000 miles, no a/c, 3.45 gears

Problem: While driving (30-40 mph 3rd gear, 40-45 mph 4th gear, 55-65 mph 5th gear) the engine will loose power as if it has died, normaly downshifting and flooring it brings back the power. Once and a while the problem has lasted long enough to force me to pull over. Engine has never fully died and the service engine light remains off. The the throtle also sticks in the no throtle position and octain knock has become a frequent problem in the last 3000 miles. The engine always fires right up, has new plugs, wires, and air filter.

Any suggestions would be greatly appreciated.

so when youre at a steady pace, do the rpms fluctuate irregulary? or does it just lose power and die down

I just loses power and acts as if it has been shut off. The RPM stay smooth, though drop off with the drop in power.

the t.p. sensor could be getting stuck as a result from the throttle sticking. the lever in the throttle body needs to be lubed with oil. take the cover off the throttle body and remove the cable and feel the lever action. if it is tight,squirt some oil on the rod and work it in.

I have a very similiar problem, though not as pronounced. The truck is a 93 ranger 3.0l five speed 4x4. It seems to not have a lot of power in 3rd and fourth gear but has tons in first and second. Also in 3rd and fourth at high rpm or under medium loads it has this really annoying octane knock, that i can't seem to get rid of. People have told me several things cause this (and i have tried higher octane fuel which only slightly helps), the most common they tell me is a very large carbon buildup in the cylinders, but i have run through countless bottles that claim to get rid of this buildup. I was wondering if anyone has any other ideas of what may be causing this. Thank You

many older Ranger owners do a simple mod called the Hot water Bypass that helps stop pinging. there are two coolant lines running through youre upper intake manifold. what you do is simply disconnect those lines from the manifold and directly to eachother using some kind of small water pipe connector. they are there to prevent throttle icing, but that isnt an issue anyway. This makes youre intake alot cooler, and can also increase HP.