I'm having a problem with my 1997 F150 4.6L 4x4. I picked up this truck back in July. I was getting a p0401 code I replaced the 2 front O2's sensors, EGR, DPFE. After that I got a p0171, p0174 code. I changed plugs, wires, air filter, pvc, tps, gas filter and the plastic tube for the pvc valve. Cleaned the MAF, cleaned the throttle body holes for the EGR. And still get the p0171,p0174 code. From reading in this site I saw that may be vacuum leaks.
My buddy got a 1998 into his junk yard and I went and got parts from it. I also took all the vacuums from the engine that run from the EGR to where it connects to a black box under the battery and replaced them. Now my truck has lost a lot of power, will not spin the tires from a stop. I cannot go back to the vacuum lines I took off, because I broke some if them.
The get up and go got up and went.
What did I do wrong?

Jeff

 

On my friends 97 4.6 4x4 we took his throttle body off and cleaned it b/c his gas pedal was sticking. after we put it back on his pedal was fine but the truck had no pick up. He said when he floored it it was like the throttle was not opening all the way. Then his check engine light came on. He drove around for a day before he brought it back over and the problem worked itself out.

I think we did something to the TPS but not sure. Is there any hesitation at idle? I forgot to plug a vacum line back to the intake tube on my mustang once and it idled like **** but when you gave it gas it was fine.

Wish I could help more but I don't know what else to change out. You might have to end up taken it to the shop.

 

No it Idles at 1000 rpm's in park, 800 in drive. It's just from a stop there is not as much power as there was before I changed out the pcv hose.
I took the pvc out of the valve cover today and it started running real bad. Put it back and it cleared up.

 

It was the new fuel pump that I installed back in September. Was
only about 17 lbs of fuel pressure. I've got all my power back.