its typical not to see gas in the filter....when car is warmed up, you wont see gas in filter....I noticed the same thing 10 yrs ago....mine was totally empty ,couldnt figure out how it was running...the gas goes into 'gas' form earlier....and you wont see it...= normal. one way to eliminate that problem ,get a steel filter and you wont worry...I would get a steel filter anyway , peace of mind, as a glass or plastic can break, and then yiou have bigger issues.

now, if you have stalling issues ,thats another story alltogether...