Airbrush problems

Ok quick question about airbrushing.

I have a paasche VL3 airbrush, and I am trying to paint my car model. I put the other tip into the airbrush to be able to spray wider, but for some reason, when I start painting the paint comes out in a thin line, and splatters. I thinned the paint also, and put the air preasure to about 60-120 PSI. The paint I am using is testors flat black. What do you guys do when painting your cars/ models? What is your setup and so on?
Thanks,
Chris

25-30 psi usually works for me.60psi seems a bit on the high side.I sometimes drop down to 15-20psi for finer work.Steve.

You said you changed the tip, but did you also change the needle and nozzle? Don't forget, on the Paasche, you need to match the needle, nozzle and "cap". All three have to match up (i.e. needle #5, VLA-5, and VLT-5).

yeah I changed the needle, I wasn't aware I needed to change the tip and cap also, I have no other tips or caps that came with the airbrush so that obviously means I need to buy them, would you all recommend just buying a single action airbrush to paint the car one solid color?
Chris

I strongly recommend against a single action airbrush, you sacrifice a lot of control for the convenience.

How your model can hold in place when you blow 120psi on it ? :D

Seriously, this is WAY to high. You airbrush can't take that much pressure. I usually work between 5-30psi on my Iwata.