Is the flame temperature of a burning fuel affected by pre-heating the fuel?
Yes and no: preheating a mix a little bit may increase the final temperature somewhat, but adding even more initial heat has a decreasing effect on the final temperature.

There are two competing factors that limit the final temperature in a closed system:


The total amount of energy as the sum of the initial amount of thermal energy and the chemical energy, divided by the thermal mass [mass times heat capacity] of the system, and 
The tendency for a reaction to be forced backwards by applying additional energy. 


For example, $\ce{2H2 + O2 -&gt; 2H2O}$ + 286 kJ/mole, but water dissociates more as the temperature rises. At 2,200 °C water is about 3% dissociated. At 3,000 °C  it is about 50% split, so half the chemical enegy is unavailable.

BTW, thermodynamically, a heat engine produces power based on the difference in temperature, so preheating a fuel-air mixture actually decreases efficiency, though it might be needed to vaporize the fuel (e.g. in Otto-cycle engine in cold weather).