panzer,

Most fully-stocked auto parts stores have at least three different thicknesses of traditional fiber/paper gasket material ... you might get some of each and try making three different thickness replacement gaskets to go between the thermostat assembly and the injection pump. Start with the thickest first, just to see if if affects your cold-running richness problem.

Hmmm, now that is an interesting thought. If my thinking is correct, I would want as thin a gasket as possible to advance the process of the thermostat, correct?

This thread seems to be repeating itself ...