1991 Chevy Blazer Runs Hot - Intermittantly

210 really isn't that bad. Make sure the timing is accurate and the distributor isn't lose. Let me know what you find.

Also, when it runs hotter, does it happen at any specific time (in traffic)?

I will check the timing, although I don't think that is it becasue it is only an intermittent problem - half the time it runs perfectly. To me it seems like it is a bad sensor, or the ECM is getting bad data and reverting to some baseline settings.

The temperature at 210 by itself doesn't bother me, just that it doesn't seem to run as well in general when the temperature is hotter. I think the 210 temp is a symptom of something else, and isn't the cause of the problem.

It doesn't seem to matter what kind of driving i am doing - sometimes it runs at 210 and sometimes it runs at 185, with no reason. For instance this weekend i went hunting and went over McDonnel pass in the morning and it was running hot and not running very well. When i came back over the pass later that day, it was running well, and I went over the pass at 65 mph wit hno problems.

I'll get back to you on the timing. Thanks.

Is there andy chance the catylatic converter is lose inside and partially blocking the exhaust?

Could be - i'm not sure how you would check that, but i'll see.

The timing is at 1-2 degrees advanced.