Flat spot.

I have a 1996 4.0 running on LPG.

Question, Is there a way of remapping the engine to improve power and remove the horrendous flat spot at 2000 rpm whether on petrol or gas without knackering the transmission.
I was gonna upgrade the Plugs at the next service (suggestions for make and model be helpful) and maybe upgrade the HT leads to better ones. (again makes and suggestions welcomed). It just needs a bit more OOMPF!

Answers on a postcard please.

Not sure if it helps, but my 3.9 classic on Gas (I know we are talking 4.0 P38) but I used 4core Split-Fire Spark Plugs (the ones with 4 electrodes and V shaped Centre Core) with Magnacor Leads.

LPG can be unforgiving of poor quality ignition components, and I blow a number of pipes and a couple of MAF's due to back firing from poor ignition....

You could try tweeking the Gas mixture to ensure it is not running to lean. only a smidge mind as over Gassing can be fatal due to detonation.