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.

 

2 possible things. your i.a.c valve may be dirty. yor e.g.r passages in the throttle body might be clogged. both are fairly easy fixes.

 

Welcome , what numbers where you getting from the Scanner PO401, PO402 ,PO406 ? Do you remember which one it was? That would help allot..

 

See this thread: https://www.f150online.com/forums/sh...d.php?t=290210

FWIW, you may have multiple problems.

Steve