I have a 2006 F150 SuperCrew XLT with 4.6. Original owner, with 258,000 miles. About a year and a half ago, I lost fuel pressure and changed a few things on the truck. I changed the fuel rail pressure sensor, the full pump module under the spare tire and finally the fuel pump and fuel filter. Over the weekend, I just lost power under acceleration. The truck would idle, but would lose all power when accelerating. I did get the P0190 code indicating the fuel rail pressure sensor. I changed it, made it home, and it seemed the longer I drove it, the better it ran. Then yesterday, it started right up, and runs fine at idle. Under acceleration though, it loses all power. It would not even spin the tires on gravel. Are there any suggestions on what the issue may be? I have not checked any fuel pressure readings (I do not have a machine for that) but am wondering if it could be something as simple as a fuel filter. I was about to put the trucks 3rd set of spark plugs in as it is nearly time for that. I need some helpful suggestions please and thanks.

 

The tool you need will tell us, the desired fuel press and the actual fuel press.. Until we have that info, we know nothing and will continue replacing possibly good parts with possibly questionable parts.
Considering what you have invested so far, very likely would have paid for an accurate diagnosis.

We don't know the condition of the rest of the engine without a good compression test. Worth considering with that mileage.