HERE (http://www.lrenthusiastforum.com/ubbthreads/showflat.php?Cat=&Board=UBB1&Number=268569&page=0&view=collapsed&sb=5&o=0&fpart=all)

looks like the right reply has already been given - take it to a good tune shop with a dynometer.

Not sure if the flapper system has a fuel pressure regulator (most EFI systems do). Mine had partially failed causing rich condition particularly at idle. They have a rubber diaphram that gets stiff or cracks over time. Also check engine vacuum at idle. The fuel pressure reg. relies on vacuum for function. I have 15"/Hg at idle (probably should be closer to 18), but seems to be running well now.