CB Troubles, What am I missing?

I have an older Realistic CB mounted in my pick-up with a brand new Firestik 3' NGP Antenna.  The new antenna has helped significantly, but not nearly enough.  I'm getting an insane amount of interference any time the truck is on; and both with the truck on or off my transmitting range is horrible, not more than 1000' at best.  I don't know much about CBs, just enough to get by and I just can't figure this out.  I assume the new antenna is fine.  I don't have an SWR meter, but I tuned it somewhat, by hand.  Could it be that I'm not pulling enough power?  But that still doesn't explain the interference.  Any ideas would be great, I use the CB often on trail rides and this is getting to be a real problem, dangerous if I end up seperated from the group.

Make sure your antenna is properly grounded. Double check the installation instructions. You can check your SWR by going down to Radio Schack and picking up a meter for a few bucks. If it's over 3 you have a problem with your antenna setup. If it's below 3 and you still have problems transmitting, it's your radio.

It's an NGP antenna, so the grounding 'issues' don't apply.  SWR is in range.

You're gonna have to help me out here, I don't know much about the names... whats the UHF connector?  I installed everything according to the directions.

The UHF connector is the part on the cable that screws into the CB.