Last week I installed an air intake system on my 2001 F150 Supercrew 5.4L. I bought it on the web for $38.00 and installed it using online intructions from another manufacturer. For all appearances they contained all the same components. I disconnected the battery as directed to reset the engine computers for the new air flow. Runs great, good throttle response and noticeable zip. MPG went from 15.3 to 17.8 first full tank. Problem - Check engine lite has come on and when vehicle is first started for the day has a tendency to stall. Idle RPMs are about 400-500 throughout the day. Any suggestions?

 

Make extra double sure you have no vacuum leaks. Check each vacuum connection for cleanliness and tightness.