I have read alot of posts the last couple of weeks on the 90HP range idle problems. All of your hints finally made sense to me and my problem. The motor starts and then begins to "load up" and run rough. If I open it up, it runs on maybe 2-3 cylinders for about 15 seconds and then the third and fourth kicks in. When I stop it idles very nice for about 30 seconds and then loads up again and idles rough. One post talked about being able to hold your hand on the block and the temperature, mine was very cool. Opened up the t-stats housing this morning and both are stuck open. I'm sure this is my idling problem, the symptoms made me think electrical and then carburation and I have been down many roads. The engine running cool was not helping proper combustion. Hope this helps someone.
