MUSTANG SPUTTERING AND LOSS OF ACCELERATION AT LOW RPMS

My car was being fixed at the body shop they decided to spray underneath the hood!!! The entire K&N air filter was waterlogged. Later that day the check engine light came on and read that read number 6 spark plugged was blown etc. I replaced the filter and also replaced the spark plugs + cleaned and dried out the throttle body. I left the hood open in the sun for the day. The check engine light is no longer on and the problems seem to have gotten a little better. HOWEVER STILL after letting off the clutch it shakes and sputters and continues to shake until the RPMS get above 2,000 to 3,000. What else could be causing this. ALL SUGGESTIONS WELCOME PLEASE. Im thinking i should have replaced the COIL PACKS. PLEASE HELP.

The only check engine code that came up said that the number 6 spark plug was bad. I replaced all of them.

so you dont think its anything with the coils. what exactly makes you think its the MAF. When i put in the spark plugs i had to disesamble the entire throttle body and I cleaned it all.

Original Code

Original code before I changed the spark plugs was P0306.
Probable cause
aa1. Ignition system fault-spark plug (s), ignition wires, coil.
aa2. Vaccum leak.
aa3. Injector Fault
aa4. high or low fuel pressure.

Whats most likely and least likely and how should i go about fixing this.