Renault Kangoo Glow Plug/electrical fault light and loss of power?

i have a renault kangoo 139d 2002 (non turbo) we have changed the engine on the van as it got flooded with water and bent the crank.
just had all the faults cleared
the van will now run fine for a little while then will not rev and goes into limp mode, we then have to stop turn the ignition off and start again, the intervals between this happening is getting less and less:
*it splatters at low rpm but no black smoke out of the exhaust
*goes into limp mode, will not rev
*Glow Plug/electrical fault light comes on
*there was a recon fuel pump on the new engine, there fore we used it with the engine but changed the electronics which go to it with the existing ones an the van.
*fuel goes to each injectors

its a manual fuel pump on the van (lucas pump), it splits into four at the pump for the injectors.

have removed and cleaned all sensors to the engine

the immobilizer light did flash until we got the faults cleared

hope anyone will have a suggestion as we have just hit a brick wall