Finally got a resolution on the power issue I was having. i.e. keeping a constant speed for ten seconds and then being without power even dropping it down a gear. Dipping the clutch for three seconds (operating clutch switch) does some reset to ECU and power recovered.

I had changed MAF, EGR, vacuum pipes to and from Modulator Valve and finally Modulator Valve which not only has cured my issue above but the car also has more power between 1500 & 2.5k rpm. As I had the problem when I got the car, I was unaware of how it should perform between these engine speeds but it did seem poor.

I managed to pick up a Mod. Valve from one that was being broken after being damaged going too fast over a speed hump. Jobs a gud un!

As I mentioned originally, that the vacuum pipes to the Mod. Valve were broken, these being damaged and not resolved sooner by previous owner, may have caused M.V. failure. I did read on a forum elsewhere that replacing vacuum pipes had resolved the issue of exactly the same symptoms as I was experiencing.

Hello,

I had this problem on my JTD130 for the first year and a bit that I owned it before I even knew what a MAF sensor was. I had a supposedly powerful diesel car that had no guts below 2000rpm and what little power it did have only happened between 2000 and about 2800rpm. I asked my friendly local mechanic when I was having the oil changed and he matter of factly said 'Have you tried unplugging the MAF sensor?'. Once he pointed out what he was talking about, I did and my car was suddenly very fast and needed far less gear changes. Imagine my delight when I fitted a new MAF and found that the car was faster still!!

Mines playing up, is fine one minute then next there's nothing, and you're being overtaken by an asthmatic grandma on a pushbike! MAF was disconnected when I bought it, and after plugging it back in, has had the symptoms above, however on disconnecting it again is still the same