engine momentarily dies, CAT light comes on
 

On light throttle lately my car dies for an instant and the CAT light comes on. No codes show up. Clues?

vag scan injectors and voltage measuring blocks-run log until it happens
 

then you may be able to determine wether it is electrical or fuel.
does it only happen at idle or under load?
there is an air control for the injectors valve at address 035 and an idle air control valve that may be faulty[this requires manual check]
If you need doc please email me

Yes, sounds like it could be an air leak on the intake

check your engine speed sensor
 

part #077 905 3801C
I had the same issue. My car began to get progressively worse

Did it go into limp mode? When I put my cone filter in. It was a really hot day and the rubber
 

hose must have stretched a little to allow the cone filter to slip off, with the MAFS causing CEL, and PRND43 to light up.

Re: check your engine speed sensor
 

Do you mean the one inside the tranny?