Any suggestions on this one guys.

Bringing misfire code up 1&5 only happens on kick down over 4500rpm.

It's had a lpg conversion so access to things is even more limited than they normally are.

(Fault happens on gas and petrol)

Checked timing is correct.
Compression ok.
Found rear rocker cover was leaking into plug holes.
Replaced gasket and cover.
Checked plug gaps (only replaced last year) but swapped Over with front bank. No change

Was getting a strong spark
Fitted Bosch coil pack as customer purchased after us saying its possible but needs further testing.

Smoke tested ok.
O2 data seems ok.

Looks like going have to find a way round all lpg wiring to get in with scope

But any one seen something similar before.

Weird how it's only affecting 2 cylinders and not the 3