[Manfred]

...We sprayed some liquid over the exhaust and the vaper stayed on cilinder 2 and 4 so maybe the firing order is wrong.

The ignition system is, that
cylinder 1 and 4 ignite in parallel,
and cylinder 2 and 3 ignite in parallel.
See below,
13 = cyl. 1
14 = cyl. 2
15 = cyl. 3
16 = cyl. 4
colours:
B = Blue
R = Red
Gy = Grey
Bk = Black
G = Green

You should check this first.

 

[Manfred]

... I guess bougie is spark plug?
If so, my recommendation is to use NGK CR9 EB,
but others might recommend other spark plugs.
I have tried all ( ! ) alternatives,
even the Champions, plus Iridium etc etc,
and I always come back to the NGK standard,
they make less problems.

Use the spark plugs with the bulb head.

 

[Manfred]

I use all of my spark plugs with the cap,
and the connection to the plugs is perfect.
With the standard coil plugs, the connection is always good.
You should check the safe connection between connector and spark plug
when the spark plug is out of the engine.

 

[Manfred]

No.

just my 2 cents

 

[Manfred]

You have a PM
with download-links for the engine-, chassis- and users manual

 

[Manfred]

... synchronise the the throttle body any tips for that?

Yes,
check the chassis manual
THROTTLE BODY ADJUSTMENT AND TUNING
(Tickover check, CO synchronisation and check)

 

[Manfred]

You will need a synchronizer.
There are many on the market,
I use an electonic one,

SynX Der Synchrontester SYNX SYNCHRONTESTER CLASSIC, ELEKTRONISCH (louis.de)