Is P0088 the only fault code?

It might be an idea if you have an IIDTool or other suitable diagnostic tool to monitor the crankshaft position sensor in case the sensor is faulty as it's a known failure point in earlier 4.4 engines.

I maybe wrong but does blanking and a delete on the EGR on these engines mess up the DPF settings?

But if the Crank sensor was Faulted surely it would not start. Mercedes AMG w207
E class Cabriolet
Overfinch L322 4.4 tdv8
1987 sierra rs cosworth 3 door white.
1985 escort rs turbo series one.
1992 sierra sapphire 4x4 cosworth red
1993 sierra sapphire cosworth 4x4 silver
1993 sierra sapphire cosworth 4x4 white
1995 ducati 916sp.

Quite a few instances reported on this forum where the engine either momentarily doesn't run properly or intermittently stops without recording any faults. The sensor part number was superseded in later engines suggesting that the sensor was improved.

It starts every time just will not rev up,until warm. Mercedes AMG w207
E class Cabriolet
Overfinch L322 4.4 tdv8
1987 sierra rs cosworth 3 door white.
1985 escort rs turbo series one.
1992 sierra sapphire 4x4 cosworth red
1993 sierra sapphire cosworth 4x4 silver
1993 sierra sapphire cosworth 4x4 white
1995 ducati 916sp.

Have you determined if diagnostics can show the fuel pressure? I'd be monitoring a few sensors using my IIDTool on cold start but if no joy then on every drive until a significant better or worse event occurs.

I have a Snapon Solus Edge,going to try some fuel pressure readings tonight,will have to Google what the pressures should be. Mercedes AMG w207
E class Cabriolet
Overfinch L322 4.4 tdv8
1987 sierra rs cosworth 3 door white.
1985 escort rs turbo series one.
1992 sierra sapphire 4x4 cosworth red
1993 sierra sapphire cosworth 4x4 silver
1993 sierra sapphire cosworth 4x4 white
1995 ducati 916sp.

From the WSM - the pressure control valve.

https://www.fullfatrr.com/gallery/albums/u...0valve.pdf

Note the last paragraph.

All of those have been changed. I took the Injectors, Fuel Rails and Pipes off Last night and sent them off to be cleaned and checked,will update when its back together. Think i might replace the Fuel Pressure Control Valve in case the new one is faulted,many thanks for your Help. Mercedes AMG w207
E class Cabriolet
Overfinch L322 4.4 tdv8
1987 sierra rs cosworth 3 door white.
1985 escort rs turbo series one.
1992 sierra sapphire 4x4 cosworth red
1993 sierra sapphire cosworth 4x4 silver
1993 sierra sapphire cosworth 4x4 white
1995 ducati 916sp.

Update. 5 Injectors Faulted, so new ones ordered. Mercedes AMG w207
E class Cabriolet
Overfinch L322 4.4 tdv8
1987 sierra rs cosworth 3 door white.
1985 escort rs turbo series one.
1992 sierra sapphire 4x4 cosworth red
1993 sierra sapphire cosworth 4x4 silver
1993 sierra sapphire cosworth 4x4 white
1995 ducati 916sp.

Fitted new Injectors and Exactly the Same.
Will only rev up after running for about ten minutes ,got the same codes p0193-17 and p0088-17,also if the fuel rail sensor is plugged in it will not start. Mercedes AMG w207
E class Cabriolet
Overfinch L322 4.4 tdv8
1987 sierra rs cosworth 3 door white.
1985 escort rs turbo series one.
1992 sierra sapphire 4x4 cosworth red
1993 sierra sapphire cosworth 4x4 silver
1993 sierra sapphire cosworth 4x4 white
1995 ducati 916sp.

Not good and implying that the HPFP itself may be the cause. I wonder if it's had a dose of petrol and driven until damage was done to the pump and injectors.

It might still be worth trying another regulator.

Have you confirmed that the return pipe isn't blocked?

I have booked into Land Rover to see if they can Diagnose it, there is the original Regulator in the car i might try it back in.
i will also check the Return pipe,Cheers Buddy. Mercedes AMG w207
E class Cabriolet
Overfinch L322 4.4 tdv8
1987 sierra rs cosworth 3 door white.
1985 escort rs turbo series one.
1992 sierra sapphire 4x4 cosworth red
1993 sierra sapphire cosworth 4x4 silver
1993 sierra sapphire cosworth 4x4 white
1995 ducati 916sp.

You know like on carburettor cars they needed a choke to increase the air/fuel ratio to be able to rev when cold? I don't know which part of these engines does a similar thing but I know until it reaches normal temperature some sensor tells it to hold on to gears longer. I thought I'd read something about the glow plugs doing something similar. It just sounds it needs more fuel until it's warmed up. Engine temperature sensor?

Cheers Kevin,all temp sensors reading correct,air butterfly flap also working fine,not sure if the air change over valve is working though. Mercedes AMG w207
E class Cabriolet
Overfinch L322 4.4 tdv8
1987 sierra rs cosworth 3 door white.
1985 escort rs turbo series one.
1992 sierra sapphire 4x4 cosworth red
1993 sierra sapphire cosworth 4x4 silver
1993 sierra sapphire cosworth 4x4 white
1995 ducati 916sp.