1993 150 intruder engine miss

I have a 93 evinrude 150 intruder and when I take it to the lake it will start and run fine but when I idle out the no wake zone and start to give it throttle it will start missing and will barely get on plane, in a minute it will smooth out and start picking up speed then when I go to trim the motor up or down either one it will almost shut down because it will miss so bad. After letting go of the trim switch it will smooth back out and run fine until you touch the trim switch again. after 5-10 minutes it will run just fine even trimming the motor and will run fine the rest of the day. Take it back to the lake the next day and it will do it all over again as the day before. This thing will do this 90 percent of the time that it is taken to the lake. Does anyone have any idea? I have had this looked at by several certified evinrude mechanics and no one has helped it yet and out several hundred dollars.

Certified mechanic does not always mean a good mechanic. Get it to someone who is good at diagnosis and have them fix it. It is not a good idea to keep running it in the condition it is in or you might just seize a piston (expensive) it is a two stroke outboard not a car.

A good rule of thumb for a shop is the fix it right the first time and stand behind it. If they don't promise that and they don't have a good rep steer clear.