So.....I followed the "How To" on cleaning my EGR valve. The EGR valve, to say the least, was full of crud, substantially worse than the pictures shown on the "How To". The only problem is, once it was re-installed, it worked fine for about five minutes, car was going like the clappers and then it started lagging to the point there was no power up until 2500-3000 revs.
Im thinking something may have slipped (not sure what there is to slip?) or the EGR valve just needs replacing in its entirety?

any thoughts would be gratefully appreciated.

Car is a 2004 1.9 cdti vectra (120bhp)