I would go by the coolant temp & 195 is perfect. on the temp gun someone posted about using a piece of duct tape on shiney surfaces to get a good reading (iirc). If you ground the coil wire that will take timing/DCR out of the picture and then do cranking voltage for the battery/cables. starters are weird electrical devices in that the slower they turn the more amps they draw & this compounds in a matter of seconds till you are down to slow cranking or machine clicking of the pull in/hold in circuits in the solenoid. EDIT the battery is always the starting point, do you have another known good battery that you could borrow for a quick test. I've heard bad regarding Optimas' (but we are the fixit dept so we get nothing but bad) with a few exceptions. MORE EDIT you might put a torque wrench or just a breaker bar & a 1&1/4" socket on the crank bolt & check it when hot, then when cold. the more info the better