Mercury 200 doesn't run good in the water

[SilverSS07]

No I had never run the motor in water before buying it. Yesterday was the 2nd time I took it to the water. Hasn't run properly in the water since I bought it. The serial number on the powerhead says it's a 1988 mariner. Has horizontal reeds. Chrome bore. I've got some pictures on my phone I'll try and upload

 

[SilverSS07]

Just to update the thread I finally broke down and took it to a shop. Timing was off and the timer base was not moving as much as it should. They water tested and said was a little slow to plane but ran ok otherwise. Took it out this morning and it would idle for about 1 minute before shutting dying unless it was given more gas. Was a little slow to plane and sputtered a little but got up and planed out ok. Then I decided to run it without the cowl. What a difference! lol Strong holeshot and pulled hard. Tach seems to still not be reading properly so didn't run it flat out but cruised around for about 1 hour at 30-35. Plan on pulling the powerhead soon to check the gaskets and exhaust seals.