I have a 1989 mercury 135 v6 outboard that has me puzzled. When there is a strong stream of water coming out of the tattletale, the motor runs right on H(ot) as indicated on the temp gage. The water coming out of the tube is steaming as well. At other times, there is weak/minimal flow coming out of the tattletale but I can run the motor wide open and only get up to 3/4 scale on the temp gage. I snipped the centers out of the thermostats (recommended by a merc dealer) and the motor is still running hot. Any ideas on what may be causing my problem? The water pump is 1 year old and there is probably less than 200 hrs on the motor.