I have a 1997 f-150 (5.4L)and recently the check engine light came on so took it and had a diagnostic run on it and i was told the egr valve was bad...so i replaced the valve but there was still a code saying egr valve insufficient air flow...i have since then changed the egr valve again along with the sensor and i keep getting the same code...when im idling the engine will start to shudder like its going to stall..and if i rev it to about 1500 rpm's its starts to studder and drop down to about 500 rpm's on its own and also going through town about 35-40 the truck starts to jerk a little as if the motors stuggling to shift....... any suggestions would be appreciated.

 

sell it and buy a GMC.... uh I mean um... fit... it....

Nah but seriously, did you check to see if any of the vacuum lines were clogged or cracked? Never had to fix an F-150 so not familiar with the common problems with them but atleast that's a start. Possibly try to check and make sure all of your sensors are plugged in, and make sure you are getting fuel. I know from working at a local shop that just because a scanner tells you one thing is wrong doesn't necessarily mean that is the problem. It just means that particular device is having a problem due to whatever else.