Ford Ranger 2.9L Auto low on power

I've done a little research on this and I'm pretty sure it's not the cracked heads. The spark plugs don't look steamed cleaned and the oil and coolant don't seem to be mixed, checked dipstick and oil filler for the 'brown snot'and didn't find any. I had a '94 Explorer that had similar simptoms, but that one you couldn't rev it past say 3500 rpms or so in park or nuetral as well as any other gear. THis Ranger you can though. I tried running Lucas injector cleaner through it 3 times and ran 91 octane for a while(At least 5 fill-ups) but it didn't seem to help. I had a '89 Ranger with the same 2.9L V6 but with the 5spd and it seemed to have waaaay more nut taking off from a stop and going down the road. Also the 5spd got much much much better gas mpg than this one. I changed the plugs, cap, rotor, fuel filter, air filter. And misted water onto the spark plug wires to see if they were cracked(a suggestion from someone so I don't know if that rules out the wires I haven't ohmed them out). The old plugs didn't look like it had been running rich. I'm wondering if maybe a sensor has just gone bad or something? I still have to check the compression because that will tell me a lot, but it doesn't run really rough only the occasional random seeming hiccup(miss?). Also it occurred to me that if it was running really rich but had cracked heads it would clean the plugs so that they looked ok. Except they look tanish and brownish which I thought meant that everything was burning the way it's suppose to? Any suggestions please? TIA~