I need more help on this Merc 3.0 I/o . I started this today and it ran for about 10 mins and the temp went to 160 and no higher and It did not idle good. Next time I started it about an hour later the temp went up to 220 . I adjusted the idle but it still idles rough. My question is could the temp sending unit be bad ? what is the cause of the poor idle?
