Had a weird experience tonight. Took a turn hard and my car started hesitating and bogging, throttle response was also lagging. Came to a stop light and my idle was surging. I took off slowly and put the clutch in for a gear change and the engine died. I pulled off to the side and popped the hood to find my air filter had fallen off. I put it back on and started the car and it ran great the rest of the night. Anyone know why i had the exact same symptoms as a vacuum leak when the filter fell off? Since it's before the MAF sensor I would figure it would make no difference if the filter was on or off.

 

Engine went into "shock"after the filter fell off(why did it fall off?Clamp not tightened?).
Put it back on,engine sensed all OK.Similar thing to me years back when I installed
a PCGR.Did not tighten the clamp on the hose attached to the filter enough.It fell off.
Car running crazy.Put it back on,was Ok.Lesson learned,retighten clamps and retorque
stuff after they are on the car for awhile.

 

The filter will restrict air flow. When it's removed you will be getting more air to the engine so it was probably running lean. Lean explains the surging at idle. We call it "lean hang" in the bike business.

 

The filter fell off because the plastic coupler had melted (home made coupler). I fabbed a metal one and the engine seems to be running fine now.