I have a 2006 F150 Crew Cab and it has 92,000 miles on it. It started off with everytime I had to get on it to pass someone and the RPMs were around 3500 it would kinda seem like it was misfiring but when it retuned to normal running at normal speeds to would run ok. So i assumed that it needed a tune up so after 3 broking plugs and $650 later truck gets worse now when I'm driving and it reaches 3000 RPMs it pops and cracks and has no power. When I'm driving it normal it is very sluggish and seems to have no power. So we have replaced the fuel filter because it was very stopped up but has not changed. Also the truck is shown codes which are P0172 and P0175 which one is fuel trim bank one and the other is fuel trim bank two and it says if bank one and two are set together than suspect fuel pressure. I also got a P0420 Catalyst Efficiency Low Bank 1. We have already checked the Catalyst Converters thought they maybe clogged but we un hooked the exhaust and drove it and it still did the same thing. Does anyone else know what it could be before i have to take it to the dealer. It also now has a whistling noise at 2000 rpms and it dont start doing that until it gets a little warmed up. This thing is driving me crazy.

 

what about the fuel pump? also check all the lines and make sure there are no small leaks, as well as the injectors. The plugs won't make a difference for fuel pressure, that would have possibly helped a misfire, but not pressure...

 

the first 2 p codes are rich fuel codes and the cat code is for low system efficiency,, if it was a fuel pressure regulater u would see drivability problems at almost all rpms becuse you always have the same pressure, the injectors control fuel at diffrent rpms,,its really hard to pin point something like this on your own because it could be so many diffrent things involving fuel delivery or fuel monitoring system so your best bet is probably the dealor