ca18det misfire backfire under load

[bigdaves12]

My det struggles to start, sluggish for a few seconds, then idles around 1100 rpm with a slight misfire, after a short while kind of after initial warm-up idles at around 800/900. When accelerator is applied it is misfiring and backfiring badly.

Things checked:

New plugs, gapped correctly
Coils swapped out
Maf removed and tested, working fine
Compression is 150 across the board
Ecu shows no errors, code 55. Did show detonation sensor but that is bypassed with a m ohm resistor
O2 sensor unplugged no difference
Previously checked the timing and was bang on

The car is at mot stage, just not running right

Any gurus point me in the right direction? I also think maybe my vacuum lines are on wrong but can't find a definitive guide anywhere