My engine has recently started to stutter anytime I'm at speeds of 20+ and I let off the throttle. I recently installed a K&N air intake and it seems to have started right after I installed it. I just changed the oil, oil filter, and fuel filter, plus the coil pack and wires were replaced a few months ago with a performance pack and wires. It hasn't tripped the engine light either. The only things I'm thinking it could be is a dirty maf sensor or a suction leak somewhere, but I'm pretty stumped as to if it could be anything else.

 

Could be the coil pack. Mustangs dont seem to like anything other than Motorcraft ones.

 

Done okay with my msd coil pack but wouldn't trust anything but that or motorcraft, id suspect you got some filter oil on the maf. Some specs on the car would help, manual, auto, any other mods etc....... Did you change the plugs as well when you did all this?

 

It's an auto and I have the same coil pack on mine. The plugs haven't been changed in about a year or so.

 

Thinking about this I'm positive its not the coil pack, it would stutter on acceleration not decel, maybe the IAC has a leak?

 

I picked up some MAF sensor cleaner and some throttle body cleaner and cleaned both of them. Seems to be running fine now. I suspect that some residue may have gotten on the MAF sensor when I was installing the intake. I have a 10 and a half hour road trip tomorrow, so I'll definitely be able to tell if it worked. Thanks for all the help!