I have been searching for this problem now for over 6 months, I have brought the car to two different shops with no luck. I have swapped in different throttle bodies, Mafs, and even coldair intakes.
My CEL is on but throws out 0505...
When driving and shifting between 1st and 5th, when the clutch is applied to switch gears the RPM's drop down to about 100-150 rpms. Sometimes if I shift quickly it grabs fine but other times if I leave the clutch applied the low rpms with cause the car to stall.
I didn't want to post this up because there are so many similar situations but I haven't seen much of this with 5 speeds when driving. I
It will also boggle down to about 450 rpms when idling at a traffic light causing the car to vibrate.

Thanks for any input, remember I am pretty certain that the throttle body is clean and working properly, along with the rest of the intake assembly.

 

Replace the fuel filter lately?

I once had a dipping idle and the FF replacement solved it completely.

Dave