Probably not the same problem as yours but my 2002 l200 animal used to go into limp mode if I used the cheap ( not red) diesel. Never went into limp mode on bp excellium or shells premium diesel. I always filled up locally but one journey I got caught out and filled at a small service station which only had one grade of diesel, within 10 miles it went it to limp mode, constantly had to pull over stop and start it. Eventually filled with premium again and all was fine. Mentioned this to a few mechanics and they couldn't explain it.