Ford Ranger 2011 Problems

By connecting the Ranger to a diagnostic computer, you should be able to work out what's constricting the engine power. Modern engines constantly monitor everything from boost pressure to fuel pressure, and transmission temperature to alternator output. Somewhere in those hundreds of parameters will be the problem and it should be fairly obvious to somebody who knows how to interpret the codes the car's computer will spit out.

Meantime, it could be that the engine's installation skipped hooking up a sensor or piece of wiring and that has caused the engine to go into limp-home mode which limits the power the car will produce in the interests of self preservation. On a really simple level, have you checked that all the turbocharger's plumbing is intact and the joints are tight post engine installation? Loose plumbing joints and cracked or split plastic tubing are a common way to lose turbo-boost pressure.

Normally this would be an issue with the glow plugs, but the 2.5 turbo-diesel Rangers seem to occasionally have an issue with the assembly around the fuel filter (which includes the water trap and primer pump) sucking in air. This can be fixed by replacing the unit as a whole. Similarly Ranger owners have reported trouble cold-starting their 2.5 TD when the valve stopping fuel flowing back into the tank from the pump fails. Try priming your fuel system a couple of times before starting and if it starts up fine then replace that valve near the fuel pump. 

How did you determine the gearbox oil was low? An additive won’t do anything for you, except maybe fix a leaking seal, but you don’t say if there is a leak present. Take it to a mechanic.

The clutch issue is not confined to the Ranger, other brands suffer the same problems, which suggests that the clutches used are marginal for towing. Your experience is not unusual, and should be a warning to everyone else looking to buy a ute to tow with. The normal fix is to install a heavy-duty aftermarket clutch, as you have done. Unfortunately carmakers have an out, in that they state quite clearly that the clutch is not covered by the warranty, and it's difficult to say what kilometres you should expect to get from a clutch before it would need replacing.

Never take anything for granted, it pays to check and check again if you’re not certain that the work being carried out on your car is what is supposed to be done. Never feel afraid to ask questions, and always remember that you are the customer, the one who has spent the dollars to buy the car.

Caltex make what they call Vortex Premium Diesel, which is claimed to remove deposits that build up over time in injectors and keep the engine running at its best. They claim that Vortex Premium will give you better performance and use less fuel, but I stress that’s the company’s claim.