Vauxhall Vivaro lack of power.

The power surge is very hit and miss with a lot of vibration at low revs. Better when cold and gets worse as it warms up.Loses power on inclines but runs smooth and with more power on the flat and down hill. No lights showing had a full service. Checked air flow regulator. Found air filter breather pipe off and not through the bulkhead. Sorted this and some improvement.Runs better at higher revs and has improved slightly today after just checking pipes etc for tightness. Any suggestions appreciated or is a diagnostic the next step. Had one injector done a few weeks before this all started.Any connection.Something not put back right or tight enough.??Thank you. Phil