hola,
  recently I sent my injectors from my tiico conversion to Marren Fuel injection for cleaning/servicing, and they told me one was bad. So, I ordered a complete new set from the Parts Bin. The old injectors were P.N. 037 906 031E, and the ones they sent for a 1992 Golf were 037 906 031AK. ETKA lists the former part number for a 92 golf. To make a long story short, when i replaced the injectors the van ran like crap. I did a few other items while the injectors were out, so they may not necessarily be to blame. 

Question: does anyone know the difference between these injectors with different P.N.'s? physically, they are identical, except the *AK ones have blue plastic tops instead of black.

thanks,
 Jeff