My 1993 Merc 150XRi idles fine and the gauge sits at 140. At above 4,000 up to WOT, she runs at 175 on the gauge. When pulling a tube at 3,000 rpm it shoots to 250 and the alarm goes off and all heck breaks loose. Shut her down to idle and within 30 seconds the temp drops and all is fine.
I've...