P2263 Ford - Mondeo MK 3 130ps TDCI (2004)

Question

Hi,
I have been having a problem recently with the glow plug light coming on and the engine going into limp mode.
When the engine is cold the car runs well, stop it and run it again and it is generally also fine. Leave the car to cool down for + - 3 hours and it is also okay. However, leave the car for only up to 2 hours and the glow plug light comes on, and limp mode.
I had a break in the stainless steel pipe going from the turbo to the EGR valve, which I replaced. At the same time I blanked off the EGR valve after cleaning it.
I thought I had resolved the problem, as I had no limp mode, and engine light on for 6 days.
I am thinking of taking the Mass air sensor out and cleaning it.
I have also noticed a vacuum valve between the MAS and the EGR valve, which I was thinking could be the problem. I assume this must be the turbo boost vacuum valve. Could this be the problem ?
I don't think the problem is a slit hose to the turbo, as I would have noticed a lack of power whilst driving, or any swoshing noise.
Please can someone help me, I'm getting really frustrated now.