The unit on top of the manifold is a by pass valve, inside is a ball and spring which lifts to allow cooling water to by-pass the block when the thermostat is closed, worth unscrewing the lid to check as these sometimes stick.

74 is the correct thermostat.

lost of use of Easy start can make the head pourus reducing the cold engine compression, so they can become addicted. if you have to use brake cleaner instead,same affect without the side affects.

otherwise i agree with comments above..