poor running

[sheppy146]

hi all
CAN ANYONE THROUGH SUGGESTIONS PLEASE
transit swb 2.5 di bannana engine
i have read on here bout opening up the air valve for more power etc etc
i done this
remove the arm from the top of the banna type system by egr valve and cable teid this open been ok for a cpl of weeks
and just as i thought this seem to be good
started to play up know running rough and no pwer missing like crap
so took of cable tie and play with the valve and put back as before
great sorted
cpl days later same thing again
so then blanked of the egr valve and that sorted nothing
so could anyone have any ideas PLEASE
cheers sheppy