If you've got the diagnostics lead, then go ahead and have a look.
Do check the vaporiser pressure - they do tend to drop a little after a few months running.
There will be a screen that lets you see all the pressure and temp parameters on the software somewhere.
See if the LPG fuel pressure is dropping under load ( it shouldn't.)
Also, you should be able to see the exhaust gas sensor feedback, check that you have feedback, and it's not stuck rich or lean. Some LPG kits show a reading of the jet size - based on how much the injectors are open. This can be a useful indication of something blocked.
Yes, you can look at the fuelling, and adjust accordingly.
But I would first look at the ignition - check the plugs - change if neccessary before doing anything else.
I chased around a "poor power on LPG" issue on my old 101. Spent ages playing with the mixers etc,. Trying to get the thing to pull properly on LPG. Changed the leads ( which looked literally like new anyway) and problem was solved by the leads alone...
LPG will find any ignition weakness...
Also, if you've had the conversion for some time - change the filters, and clean the LPG injectors (by disconnecting the injector feed pipe, squirting some carb cleaner, or petrol into this disconnected LPG feed pipe, reconnecting, and running her up on LPG.)
When I do this, I do run the vehicle up to speed, and changeover to LPG at over 50 ish mph, so the engine cannot stall - it will stumble, as it pulls the cleaner fluid through, but this is only temporary.
Yes, LPG injectors can seem noisy - this is normal.
