I have a Merc 260 in my Formula. I am having a hard time getting it to idle at 600-750rpm. It will idle perfectly at 900-1000, if i adjust the throttle screw to lower the idle, the engine stalls. I did some troubleshooting and determined the electric choke was not getting power. I hooked that up and the choke housing gets hot. Is that normal? I am now able to get the idle to 750 rpm. The idle mixture screws however make no difference on any setting except all the way screwed in, then it stalls. I have never owned a carbed motor before. Any help would be appreciated.

choke housing has to get hot,thats what opens the bi-metal spring and opens the choke..you have a vacumn leak if you can screw in and screw out the needles without any reaction of rpm,s

+1 on the vac leak . With good ventilation , spritz some carb cleaner around the base of the carb and also around the sealing surfaces of the intake while the engine is idling . If the rpm increases then you found your leak . WD40 will also work and won't be harmful to your engine paint .

I tried wd40 everywhere with no change in rpm. I sprayed it everywhere I could see gasket. Is it possible that the intake manifold gaskets are leaking? I am picking up a new set of Vortec heads tomorrow. Maybe with the top end being new the problem will be resolved with the swap. I am assuming that the carb will be ok to bolt on a new set of heads and an RPM Air Gap intake.