Hi i have a L reg 325 td which was fine when it went to a garage for some minor mot repairs,after spending hundreds of pounds on various bits its never run right since. I replaced a fuel valve,had a hole in the exhaust welded and a new pipe fitted from the fuel tank to the filler. Now it idles okay for a couple of minutes then starts rough idling and cuts out as if it cant get fuel,after it cuts out the fuel comes back up the see through pipe from the engine back to the filter with a funny noise,when it is running it looks like the fuel going through has air in it,its sat with a flat battery for months and id like to understand what makes it cut out then start then cut out