I have a 1998 90hp outboard which starts beautifully cold. However, after the motor is off for more than 30 mins, it is hard to restart. I have replaced the spark plugs, fuel filter, water separator filter, and primer bulb. I have also run Quick Silver's water treatment and Quick Silver's engine treatment through the motor. I have tried several different ways of restarting the motor warm like fast idle, fast idle with choke, choke only with little success. This is my first boat so I am a little lost. Does anyone have any suggestions?