Need help troubleshooting airbrush problems please.

I'm a new modeler with a Badger 150. I have read as much as I can about airbrushing and taking care of the airbrush. I "think" I'm doing an ok job, but something must be wrong. I have a problem with the flow of paint or even thinner sputtering. I just won't blow a smooth stream. Even when I am cleaning the brush and I have just a jar of pure laquer thinner in it, when I try and spray it out at full "pull-back" at about 20-25 psi, it sputters about every second. Sorta like a "ts, ts, ts, tssssssssss, ts, ts, tssssss, ts, ts, ts, tssssss". It's a litte different with paint. I don't spray at full "pull-back" most of the time because I'm trying to paint in detail. But when spraying paint it will slowly, over about 5 seconds, almost stop spraying paint and then it will almost "hiccup" and spray again. I look in the front nozzle and its not even close to having any paint buildup. What I end up doing is spraying a few seconds till it runs dry and then pointing the airbrush at something else, like a piece of card board, and pulling back all the way to get it started again. This is very annoying. I "believe" I have thinned the paint out enough. It seems like milk to me. And besides, it won't even spray pure thinner out correctly. I will try thinning the paint out more next time. I clean the airbrush by attaching a bottle of pure laquer thinner (I'm painting with enamels, btw) and spraying about the whole bottle. I detach the bottle, unscrew both parts of the nozzle. I submerge the nozzle parts in laquer thinner and start cleaning the rest of the brush. I take out the needle and wipe it with a paper towel dipped in thinner. I then use a pipe cleaner to clean out the part that the paint cup and bottle attach and clean out the front of the airbrush. I then clean the nozzles. All parts look clean as a whistle. I put everything back in place and blow air through to dry it out. Then I put it up. If I'm doing something wrong, please let me know. Other things I may need to say is I'm using a the fine tip. The tip seems perfectly fine to me. It's practically new, given to me by my mother used it only once at a class. The nozzle tip doesn't look damaged either.