Nightmare continues

Having a mare with my astra 1.7cdti. One minute it drives fine the next its in limp mode and won't do above. 38mph. I've posted on here befor so cleaned out all egr valve and such things. The pedal test keeps saying it accelerator pedal but I've swoped this with two different ones and cures the problem for a day or two then it happens all over again. Had four different garages tell me four different things including a rewire job
Any other ideas I can try befor I reluctantly take it to vauxhall and spend a fortune
Any help would be appreciated