I was inspecting the inside of my petrol tank following on from my last thread on a possible blocked fuel tap / filter. When I opened the filler cap there was a gush of air released. I checked to see if the tank breather was snagged anywhere but it doesnt seem to be, and the vacuum hose is brand new with no kinks and fitted correctly.
Would the tank pressurisation be causing the fuel starvation symptoms I've been having, in some way restricting the vacuum from working properly? ( the tank interior and filter are spotless)
Any help appreciated.

sounds like the breather for sure.

try removing it completely and going for a run...bet you dont have any more problems.