I have a 97 f150 4.6 5 speed. let me start by saying it has 250,000 miles on the original motor and recently it started starting slow ... especiialy when sitting over night. and now it has no ***** at all in 3rd and 4th gear like the farther the peddle goes to the floor the less rpms i have. I replaced:
Starter.
fuel pressure regulator.
fuel filter.
all new plugs and wires.
now its getting worse. could it be the fuel pump? im already about 400 dollars into this and the truck honestly isnt worth putting more money into i just wanna knw a fix

 

do you have any codes? yes it could be the fuel pump before replacing though check the fuel pressure at the rail.

 

Yea its saying bank 1 and 2 are too lean buti don't are how that can be related to my problem it idles fine and how do I check the pressure at the rail might be a stupid question but I never did what do I need

 

Get a fuel pressure gauge and connect it to the fuel port on the rail. Start the engine and check the pressure. It should be 30-45 PSI if all is well.

Other things to check.

PCV Valve and the hose it is attached to (PCV valve is about $3 so change if old)

Vacuum leak somewhere so check hoses

Air Cleaner and MAF sensor dirty so replace and clean as necessary.

If you don't find improvement with the above, do a vacuum test. If you have a vacuum leak in the manifold gasket or elsewhere, your vacuum should be steady and something less than the normal 17 to 22 inches of vacuum. If the vacuum is all over the gauge, you have a broken engine (valve, head gasket, rings, misfire). Since you are not showing a misfire code, I am suspecting you have a vacuum leak and hopefully, something easy like your PCV valve or hose.

 

X2 on checking for vacuum leak. improper fuel pressure and or volume will also cause a lean condition though.

 

Okay thanks for the responses guys ill update you as I try these things and get time to do them

 

checking the vacuum is not to say it could not be low fuel pressure because it sure could. The easy vacuum checks for PCV and hoses are just easy to do and eliminate them as potential problems. It is harder to do the fuel pressure test because most guys don't have a gauge so I like to look at the easy stuff first and hope I get lucky and have a simple problem that is easy and cheap to fix. I have had too many instances in my life where I changed a part that was expensive and a lot of work only to find that 75% of my problem was an easy fix that I initially overlooked.

 

I have access to a pressure gauge so im gonna change the pcv valve because its so cheap and check the elbow and hoses for obvious tears/leaks and then pressure test it because the loss of power is even in second gear now when I out the pedal closer to the floor. again... thanks for responding....

 

but sometimes the truck runs fine almost like it doesn't always do it. im hoping its not in the motor its a good truck.

 

One easy way to tel if its fuel pump, is in the mornings, after it sat for all night, is just turn the key to "on", wait a few seconds, turn it to off, do that a couple times, it should prime the pump pretty good, it should start right away. This has worked for a couple of my older cars before, I don't see how it wouldn't work here. Its bot a fix, but it should tell you at least on the start up.