2.0 = painfully slow
2.3 = slow, but workable for a daily driver. Also nearly indestructable, even making way more power than they should (turbocharged).
2.5 = slightly faster than a 2.3
Note: 2.0, 2.3, and 2.5 are all the same motor with different bore/stroke combos.
2.3 duratech (2001.5+) = Pretty zippy I hear
2.8 = Lots of upper end problems and wonderful 80's carb+computer technology but the biggest motor you could get in the beginning.
2.9 = Fuel injected version of the 2.8, has a bad history of cracked heads and the failed cam bearings causing lost oil pressure. Other than that people still swear by them
3.0 = Nearly indestructable like a 2.3, but kind of gutless in the lower RPM's. People often complain they don't belong in a truck. Not a big deal with the right rear end gears.
4.0 OHV = Loads of low end torque and can really snap a 2wd ranger around pretty quick and in a 4wd they are more than adequate. In an explorer they are quite a bit slower but still adequate. Plenty of cracked heads though but it usually only happens to trucks that had a degraded cooling system
4.0 SOHC = Same torque as a OHV but with 50 more HP. They would be quicker, but about the time these came along the rangers started getting a bit heavier and Ford would only put them in the heavy 4x4 and/or supercab trucks. They're also hard on gas, with mileage not much better than a 4.6 F-150. Other than that they've suffered from some timing chain tensioner issues that are expensive to fix.
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