I know Dave will shoot me for this, but I also imagine that your particular antenna does not radiate efficiently enough to see huge gains from much of the mobile tricks to reduce noise and increase efficiency. I am not saying they can't make contacts, just that no one should expect it to perform awesomely, especially on the receive end.
The popular ones tend to be the Hamstick®, and the various copycats. All are very low in efficiency, as their Qs are about 50 or less. A few of the 80 meter models have Qs less than 10! If you want a really lossy antenna, use one of the stubby 3 foot long versions!
Their only attributes are, light weight, low wind loading (some models), and low cost (≈$20USD, less mount). This means they can be attached by just about any type of mount, some of which add to their overall losses (i.e.: license plate mount). Efficiencies range in the .3% to 20% (80 through 10 meters), and they typically don't need matching as the system losses bring the input impedance to near 50 ohms.
Blue '99 UZJ100 2" Lift, Replicated Outback stackable drawer system, Engle 63 QT, Custom Front Bumper, Gamiviti Shorty roofrack.