troubledford

First of all thanks for any ideas. I have a f150 1997 with the 4.6L romeo block, auto trans, flowmaster cat back, MSD, and K&N. With that out of the way, my truck runs great at idle/in park or neutral it will rev till its heart content but as soon as it is in fwrd or rev it shakes and gets nastier as u apply the throttle. Driving down the road it does the shake thing till u hit a constant speed/rpm. The trans was checked out and the shop said it was good (would not be like a shop to pass up money, so i trust them) Im just confused in park/neutral it feels strong and in gear it breaks my heart. I did replace all the plugs, wires, egr valve, dpfe sensor and fuel filter. Im at a loss any help would be much apperciated. thanks

97SlowWhite

vacuum leak?

cliffwva

Sometime the mass airflow sensor can get gummed up and cause this. A can of mass airflow sensor cleaner can be found at Autozone for about $5. You don't always have to spend $300 on a new MAFS when all it needs is a good cleaning. Be sure to NEVER touch the sensor with a tool or your hand, just the spray cleaner or you will be buying a new MAFS. The other thing that can cause this are the COP (Coil Over Plug) coils. I'm not sure if yours has them as you stated you replaced the wires but on my 5.4L it has them. My truck has the same type of hesitation you are reporting until I replaced them.

troubledford

any easy way to go about checking it or where should i start oh i all checked for codes and came up with nothing thanks for the help i guess i can down load a diagram of the vacuum system

troubledford

any recommended brand of MASF cleaner

cliffwva

No particular brand is needed. Just make sure it is for the MAFS. Autozone only had one to choose from so the choice was easy.

Jgiff

Help

97 f 150

Put a junk yard motor in ran great shut off after 42 miles no power to fuel pump put new pump in checked relay and fuses
Now what????

troubledford

was it a long block(all the goodies) or a short block(bare bones)

RelentlessR1

vacuum leak??

Jgiff

It was a 4.6 Romeo in an xlt. I also couldn't get the emissions system to register I'm wondering if the computer quit on me. It just seems odd it ran great for about 60 miles and just shut off on me