Loss of power

I have a Peugeot boxer TD 1.9 XUD motorhome 
Year 2000
No ECU

I’ve got loss of power below 2000 rpm, had egr valve replaced, injectors checked , still experience a loss of power at lower speeds.  Checked all turbo pipes and hoses all seem ok, replaced all pipe clips with stronger ones just in case a small leak.  Turbo spools up and kicks in above 2000 rpm, mechanic says turbo looks ok  Still loss of power.  I’m scratching my head , 2 mechanics looked at this no issue resolved.  Not smoking when running after a mile,  not overheating, smokes on starting and seems to miss slightly, gets better when warmer.
Had timing belt done along with rest of belts , still loss of power, Any ideas please? 

Thanks

Mark

Every part of me says turbo for this fault.
Mechanic says it looks ok is pointless, nothing visible is anything to do with the turbo function. Unless a casing was split perhaps.

The turbo should be providing useable boost well below 2000 rpm, indeed max torque should probably be below that.

The smoke on starting is important, willing to bet its white or grey? If turbo isn't delivering, under load, then there'll be lots of black smoke as the engine is being over-fuelled with no or little turbo output. White or grey smoke will be oil related, another turbo problem, oil can pool in the bearing area, the whole centre of the turbo, poor seals, then take a wee while to burn off.

I'd find a local diesel garage which can properly analyse turbos, a proper diesel specialist, should be plenty where you are and get it looked at my specialists, IMHO

The smoke is blue, not black and disappears after I drive a mile, it’s not always present, for example after a long run yesterday and after the van had been stood in night , I started it with absolutely no smoke. It starts well and only smokes intermittently when idling after first starting it after 10 mins if I don’t drive it , it goes when I drive . My turbo is vacuum as it’s old school, no ecu so I expect there is no MAP sensor, I also thought that it maybe turbo related , but you can hear it spool up. Two mechanics who are specialists say it’s not turbo but say it maybe the diesel pump, this is very expensive to fix, been quoted £550 plus any parts for a total recon of mine.

I was told it does not have one, turbo is vacuum managed, there are cables for most things, I do have fuse box but I didn’t see one under the dash or under the bonnet

The vacuum part of the turbo, is control for the waste gate which controls the turbo air output pressure and limits it to prevent over-boosting the engine. It dumps the excess hence the word WASTE.

Re smoke, why the fuel pump then? If it was it'd smoke every start and perform the same way each time?

My 2002 turbo has a vacuum waste gate control too, no ECU, and no ODB port in the modern sense, it does have engine info from a 2 wire plug under the bonnet.

I'd still stick out for the turbo being the culprit!!!

I think Ian is right. I once had a problem with my turbo waste gate valve, which caused loss of power. This was discovered by my local garage, they stripped and cleaned it and thereafter checked it at each service. Which became the norm for any MH they serviced.