Poor running

Hi everyone, just wondered if anybody can tell me why my golf runs better when I undo the centre fuel line that goes into the fuel metering unit? It's a nightmare to start on the throttle but if u undo the nut again on the metering unit it runs like a dream, but u loss loads of fuel. Once u do the nut back up it runs fine for two minutes then goes back to running terrible, anybody any clues what is wrong? Thanks

Hi Max

Sorry for the slow response from anyone, with the AGM weekend the forum will have been quiet!

Is it a K-Jet you've got I take it?

centre fuel line as in the one on the front? or on the side?