Hello,
Though this thread is a couple days old and the OP may have given, here is are some answers (a small twist may be afoot):
1. Remove the cracnkcase driven fan. While I openly admit this does not I crease the engine power or performance, it does reduce the load felt by the engine significantly. For these Ford 60° V6's, it is the easiest, cheapest way to gain some miles per gallon and some if the power and torque the boys and girls @ Ford engineered out. Pics available .). To cool the use of an electric fan or pair if fans will more than be suitable. They can be controlled automatically with a Thermo sensor or manually with a simple switch...and finger .)
2. Oil cooler. If you can reduce under the hood temperatures and increase your oil capacity, you will run cooler and make better power.
3. Used the best premium fuel around. When you burn more completely, you are saving money by getting farther on less.
Inspect your lifters and push rods. These 4.0 OHV's are prone to premature failure and wear do to poor oil circulation up top.
4. A good set of headers will help the engine realise more of it's potential. You can expect an honest solid 9-12.5% improvement.
5. To help those headers, rebuild your exhaust one size tubing larger. Ex, if you have a 2" system, build a 2¼" system .)
6. If you have done all if the above, then a nice cherry on the top is a little PCM massage (performance chip or programming).
7. The engine can also be rebuilt; clean all the casting, corners and burrs, polish the crank, balance the complete bottom end, port/polish the heads and intakes, wiff-up the throttle body.
+Balancing the bottom end will provide a non-deminishing 10% improvement in power and torque.
+P/P the heads with multi angle (as many as are appropriate) and flow match to the ported heads will yield approximately 20% improvement fir the heads and 7-12% for the intakes.
+Throttle body WIFF will yield a solid 2-3 hp across the rpm, that never goes away.
8. Replace your driveshaft with an aluminum driveshaft. Your engine will not increase in power but once again how and take engineered out is realised.
9. With all other suggestions employed, not having a custom reground cam would be a SIN!!! I suggest consulting an authority based on your needs but I always go for maximum torque which always yields maximum mpg .)
In summary, the cheapest, quickest power restoration is the removal of the crankcase driven fan. Headers are next but really need the full exhaust treatment to realise the gains. Better cooling us always going to help and of course the choice of quality components change at prescribed intervals is expected.
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