Ok try this...
Turn on the engine.... take a look at it, maybe it does a little abnormal "side to side" movement...it will be like dancing, this is what we don't want....
Now, go to the MAF sensor... just next to the air filter... in your case is a KKM (I'm actually almost stock) you will see some cables plug into it...Ok this is the moment of the true....
UNPLUG IT!!!
The engine will accelerate for about 2 or 3 seconds, (this is because you just unplugged the sensor, now it doesn't now wich is the amount of air that is coming in...) then it will be back to normal, and you will realize that the engine stops HIS dance... if it doesn't... well is not the sensor....
Go and get your cables, fuel filter, or spark plugs, I'm actually just about to clean it, but today a "Ford guy" told me that he will do it for me, for free, as I don't have the T-20 security screwdriver, I can't do it by myself....
Hope this could help you.....