Help! Won't run smooth over 2000 RPM

[Josh Adams]

First off, it hasn't thrown the Check Engine Light. 2001 4.0 SOHC 168,000 miles
Second, I replace the MAF

Here's the problem. Truck started fine and drove fine for about 4 miles and then it starts bucking on me. I let off the gas pedal and then press it again and it does it again, but only if I try and go over 1800-2000 rpm. I can get it to a desent speed on flatter ground but when a hill comes up I'm at about 20 mph all the way up it. I changed the MAF out and it still does it. The check engine light is NOT on. It started today.

I don't know if this has anything to do with it but I'll put it up anyway. I've been running the ethanol gas in it for who knows how long now and decided to try the no-ethanol gas to see if I got better mileage. I'm half way through my 2nd tank now. Would this be an issue?

 

[my98nnj]

Does it feel like a misfire? Might be the coil pack failing. Verify fuel pressure too.

 

[drdoom]

Check the fuel pressure, could be low. Possibly clogged filter or weak pump.

 

[deweyville65]

First off, it hasn't thrown the Check Engine Light. 2001 4.0 SOHC 168,000 miles
Second, I replace the MAF

Here's the problem. Truck started fine and drove fine for about 4 miles and then it starts bucking on me. I let off the gas pedal and then press it again and it does it again, but only if I try and go over 1800-2000 rpm. I can get it to a desent speed on flatter ground but when a hill comes up I'm at about 20 mph all the way up it. I changed the MAF out and it still does it. The check engine light is NOT on. It started today.

I don't know if this has anything to do with it but I'll put it up anyway. I've been running the ethanol gas in it for who knows how long now and decided to try the no-ethanol gas to see if I got better mileage. I'm half way through my 2nd tank now. Would this be an issue?

I go along with drdoom, check the fuel pressure. I bet the fuel filter is the problem. I use StarTron in my truck, have not had any fuel problems yet. Filter is the one that was on the truck when I bought it 15 months ago.

 

[Josh Adams]

Just took it and had it put on a diagnostic computer and it had 2 codes on it for the EGR. The guys at the shop said that the cat. convertor could make the EGR codes pop up if they are clogged up. Gonna try and get the cats cut off

Check Engine Light didn't come because the bulb is burned out.

 

[drdoom]

Which codes did they read?

 

[Josh Adams]

I didn't ask. He didn't read the numbers off he just read the description. And he read them off a little quiet but I know he read 1 that said ignition egr something and another that said something with the egr

 

[Fordmandan87]

i agree about the cats possibly bein clogged that fits the bill perfectly

 

[drdoom]

Always get the actual codes.

 

[Josh Adams]

Crank positioning sensor. That is the correct diagnoses. The wires had been chewed in two or something like that.

Also have to replace an egr part.

Still got 2 cats cut off