occasional stall

When i fist bought my golf tdi mk3 it was occasionally and randomly stalling so I checked for codes on a diagnostic check and all was clean. I then disconnected the ecu for 10 mins to reset it and haven't had a problem i n 6 weekssince. Except for last week, when it cut out again when easing off the gas.

what's this all about?
Thanks

that sounds like the egr is sticking in the open position.