td5 revs at idle but when in drive it hardly moves

Hi, my disc 2 td5 has no guts, its recently been playing up with intermittent lack of power, last week the head gasket finally gave up. Replaced head gasket, skimmed head, replaced stupid plastic dowels with steel ones, all back together, lovely jubbly. Pig to start after overhaul but on the button now. Went to test it and it Wold not pull the skin of a pudding. It had done this on the day it broke down with overheating, so don't think its directly related to my doing the gasket. Have checked the fuel pressure and is a good 4 bar at the pressure regulator, have tried a new maf sensor and checked the turbo valve all make no difference. When you try to drive off the revs slowly creep up, not like a clutch slip all revs no go, its no revs and no go.
Tried to diagnose it but don't have access to a nano. Can anyone please help.

Hi, as it was overheated did you replace the injector rubber seals and copper washers as well?... and the injector loom of course as you ewere already there... if the engine was overheated the injector seals were affected and there will be back pressure against the pump, the injector loom might be affected too

did you purge the sh*t out of the system with the 5 pedal method?... it's not enough only once to be 100% certain that all the air is out

fuel and air filters are new?... use branded fuel filter not some very cheap aftermarket cos it can make you trouble

Replaced the injector seals and washers, not the loom as it was fairly new prior to the overheating. No signs of oil in ECU area.
Not sure of the 5 pedal method you speak of. Have not changed the fuel filter but air filter is new, I will get a new one and try. I did not touch the adjustment on the injector tappers, is that something that needs to be checked?

yes, the injector clearances are important, 5 pedal method = ignition on pos II, depress completely the throttle 5 times consecutively untill the MIL(malfunction indicator warning lamp) starts flashing... wait untill the MIL stops(around 3 minutes), ignition off then crank

Thanks will give it a try. However I managed to get enough steam up her to take her round a nearby trading estate and after flooring it in a straight run, it did build up speed and revs till about 4000 but does not change gear. I now wonder if the auto box is faulty, and the extra strain of driving it like that helped the head gasket go. So my next task is to drain the g'box and check oil condition and quantity. Does this sound like it would fit my symptoms? And are the boxes prone to fault if so is it something I could fix w'out going to a g'box specialist.