It doesn't really sound like vacuum leak symptoms, but it's good to know your vacuum numbers at any rate. As site said, go rent a vacuum tester. You want to measure with the engine at normal operating temperature. Find where the rubber hose from the brake booster goes into the intake manifold. Loosen the clamp at the manifold, remove the hose, and attach the proper adapter included with the vacuum tester kit. Start the engine and observe where the needle sits at idle. For at or near sea level locations, I believe 20-23HG is nominal..17 is low but acceptable. I don't know much about Houston, but I know it's hot and humid and most likely near or below sea level, so the numbers on the gauge are to be read without doing math(higher elevations require a formula for factoring elevation). One thing to note in your particular situation is that you stated earlier that your engine idles at 1200 RPM. That will produce a higher vacuum reading, possibly masking any problems. My '80 ZX is supposed to idle at 750RPM(which it currently does)..I'm sure 750 is right for all the FI cars but you might want to verify idle RPM for your year.
I would research how to adjust the idle mixture adjustment screw
http://xenonzcar.com/s130/afmrefresh.html
See step 7