Help with my Omni 5000!

fellows, im quite frustrated with my 5000 as of now. i had to lay off the hobby for the last couple of weeks due to time constraints. when i have a few moments, i try to airbrush on some spare plastic to hone my skills. before the lay off, i could achieve the fine line very well with great consistancy. since my return, i cant seam to get my brush to "act" like it used to. i had great success using tamiya acrylics but i still like enamels because of the color selection. i swapped back to enamels to try the fine line and could only achieve a "morse code" type effect. i can begin spraying a line and concentrate on holding the trigger in the same position as i go along, but the paint just fades out after about 3 to 5 seconds with the trigger being in the same position. once i pass a certain point with my trigger, it begins spraying excellently. the only problem is, i cant do any kind of detail work with the pattern. i had simular problems with enamels before with my omni, so i did a thorough clean, primed the brush with tamiya thinner(i sprayed 2 bowls full through the brush), and tried my trusty old tamiya acrylics with the same effects. if i do achieve the fine line, its morse code for about 3 seconds or less and then no paint! i cant figure it out. i have tried replacing the needle and tip to no avail, tried a 3 to 4 increment increase/decrease in psi from 10 to 30 lbs, tried different ratios with different thinners, and loosened or tightened the head assembly. what gives? please make any suggestions that you feel would help. i feel like ive covered all the bases with the paint, but have i damaged a part that a rookie ab user dont know about? a very desparate and frustrated saltydog. thanks. later.