2001 Ford Mustang • V8 2WD Manual • 25,000 miles

I just bought a 2001 Ford Mustang cobra. It has exhaust, throttle body, air intake, and a few other things. I drove it home from the place and the check engine light came on and the idle was jumping from 800-3000 rpms on its own. It did it most of the way home. I hooked up my codereader and it said that the system was lean. Thats he mass air flow sensor. I brought it back and the guy said it was because the car has a lot of modifications but no tune. Is there something wrong with the car or would that be the problem?
February 25, 2011.

Lean readings can be a faulty Mass air flew sensor or even a vacuum leak, start here.


Feb 25, 2011.
Check the vaccum hose at the back of the intake next to the firewall and make sure there are no broken motor mounts if the engine moves too much it tends to pull this hose out or even break it

Feb 26, 2011.
With the performance air cleaners that can set a code for lean. You may need to have it redone electronically to richen the mix up a little or put larger injectors in.

Mar 4, 2011.