Would be very grateful if anyone has any other advice on trying to get my daily back on the road.
For a month now it won't idle properly; either cuts out as soon as you take your foot off the throttle, or may work sometimes but then cuts out after a few minutes. You also get a 'surging, engine braking' sensation when driving, although under load it seems fine and accelerates without issue.
I thought I would be able to fix this myself, the last time it did something similar I discovered an air pipe to the MAP sensor was half hanging off; re-connected it and all was A1 again. This time, despite the same pipe looking a bit loose it made no difference when I secured it. Have replaced the idle air control valve, checked all pipes for leaks, and even replaced the whole throttle body with another working one to no avail, still cuts out and has added a symptom of rev surging between 800 - 1500 revs too. I think I may have changed too many bits now and probably gone backwards. My mechanic is not sure what to do next, suggested I let a garage loose on it. He's suggested it might be the fuel pump sender unit above the tank starting to fail, well I have a spare so could try that. Or possibly crank sensor?? He doesn't see to think it's anything to do with plugs/leads as it starts fine and works on all 4 cylinders.
This is the worst issue I've had with it in four years. Bollox.