problem with 115 4 stroke yama

motor is shutting off when changing gears from forward to reverse some time`s.It does not want to run very fast at first,but then if I work the throttle it goes fast for a second or two and then back to slow.after about a mile of running it ,It runs pretty good the rest of the night.I have had the injectors rebuilt,new fuel pump ,gaskets,and two filters.It has to be something minor I hope .It is a 2001 model.ANY HELP OR ADVICE WILL BE APPRECIATED.

have you had a computer diagnostic done while running under load?

no i have not ,what do maybe wrong

not sure, which is why i would like to see computer diagnostic numbers to see if that side is working properly, then need to look at fuel pressure gauges, as well as engine and fuel vacuum numbers

chris v how much will something like that cost.

$200 plus or minus

last time I had it in the shop ,they c/o one spark plug that was cracked.It only cost 120.I think I will c/o all the plugs and see what that will do.If that do not work then I will seek pro help or pro advise.thanks for your input thats what made me think of plugs.