Have you tried 30s or 60s images. 3 minutes though not impossible is not a good place to start if you're just starting out.
Your guide calibration also is best done near the celestial equator (do an internet search) as that's where a camera will see the most star motion. If you've done one already, open the plot in your guide screen (top right button so you see the blue red graph, if calibrated right the two lines should be at 90 degrees to each other, they may be at an angle to the x y axis but that doesn't matter due to your sensor or rig orientation when calibration was done), clear the last calibration, loop your exposures again and recalibrate. It's important not to have your setup move or vibrate during calibration, don't even walk around your setup.
Sometimes for some unknown reason the asiair can turn off your mount tracking, but you'll know this is happening by looking at your guide panel and Ra/Dec graphs, the original stars will drift out of view and your graph will keep getting worse with larger numbers in RMS. Check under mount settings that's its.tracking is on and it's sidereal tracking.
Also no issue with using colour cameras to guide, I've been using my 224MC camera for guiding duties for years, mono are better as they're more sensitive so will also see stars better (also helped with larger aperture guidescope optics) but not essential.
