LPG injectors?

You don't need to double bump. Ok right so what setup do you have. You said you have dual fuel. So I'm assuming you have a ring on your air intake pipe and a converter near by? If so the injectors are petrol only and thus no different to stock. What makes you think you need to change your injectors though?

 

If you're 100% certain that is is injector's, Dont go buy new one's just get you're old ones ultrasonicly cleaned,

But before all that try injector cleaner, Even go to a mecanic and get them to do a carbon clean and a injector clean, They use stuff that can not be sold to the public, So it really work's, I did it on my car, worked a treat!

The carbon cleaner get's fed into a vaccum line wile on idle, Work's well if you're car has never had one before.

Clean plenum.
Change plug's and lead's.
Change fuel filter.
Clean maf.
After all that im sure you're car will run fine

 

What fuel do you run normally? As said though change and clean the above items.

 

What fuel do you run?

 

It's not injectors if it does it on gas as well.

 

This. The problem lies else where. If leads and plugs are fine then I would be looking at coils.

 

Does it backfire on gas? If it doesn't, it won't be an ignition fault. I'd be checking for a vacuum leak myself, Ecotecs commonly get a vacuum leak at the throttle body. There is a small line that goes into the bottom of the throttle body that falls apart over time. Start looking there.

 

Sounds like the gas system isn't perfectly tuned, might need a tweak

 

Stick with stock and you will be fine.