I have a 86 2.3 4 plug ranger 5spd 4x4, i have put a new map sensor, iac valve, cap and rotor, plugs and wires, ign coil, and timed it by the book(10 degrees before tdc after warming up unplugged spout connector, timed 10 degrees btc and plugged back in spout connector),timed by ear and no matter what i do it seems to be running rich and way down on power, got it to run great for 2 days drove it 200 miles and after it ran the same as it was before. Looking for a starting point/ any advice you think would help, Thank you.

 

Welcome to the forum

O2 sensor?
They only last 12 years or 100k miles and they decide lean and rich after engine is warmed up

Pull out the 4 new spark plugs and look at the tips
Should still be white
Darker colors mean that cylinder is running too rich so injector issue, can also be oil leaking in thru a valve guide seal