The problem may not be the T/stat. Although, changing it isn't expensive or difficult for just the sake of trying to remedy your issue. Do not omit or modify the T/stat as it will cause unwanted cooling properties such as taking too long to warm up (sucks in winter time, no heater) and once it does reach operating temp it will have the tendency to overheat from excessive coolant speed through the radiatior by not being regulated by the size of the opening of the T/stat (omitted or modified). It will also cause uneven cooling of the engine as well which is not conducive to keeping it from wanting to blow a head gasket as well. We all know how these 22R's already don't need any help here.
In fact the BSV, which controls the EGR vac circuit, basically has a T/stat built into it and operates via the coolant temp (near the T/stat housing). So it operates independently of the T/stat anyway. Which is why there was the changes made as noted in the info that BLINGN posted.
(1) Lean air fuel mixture.
(2) EGR influence on lean mixture.
CORRECTION:
(1) Operating temperature of the EGR valve BVSV has been changed from 40~C to
60~C.
I'm not saying that this is in fact the solution to the problem you're having. Just consider it strongly as a possibility since what is in this info is a step in the right direction of things to consider. Along with the other info offered in this section as well. That's all.
Other things to check as well, start with basics such as timing advance. Check for bad vac advance or sticking mechanical advance on the dist. and look to see if you don't have a bad accelerator pump or anything like that. Also does it need to be tuned up? Always start with the simple stuff and go from there. Hope this helps. Good luck fixing your rig!
Keep us posted with what you find.
