Car won't start please help me figure this one out!!!

I have a 98 gsr thats turboed. It was running fine for quite awhile, but every now and then i would lose power and when i stepped on the throttle it would be dead or very weak for a couple of seconds mid way while driving then it would come back. That happened maybe twice. I figured it was some thing electrical and tried to look for a problem, but never found it and the car ran fine. I did replace the fuel filter and I thought that was the problem it worked good for awhile, However now it refuses to start up. It cranks, but will not turn over and if it does its very weak for about 2 secs then shuts off. I notice some smoke in the engine bay not much but it alittle cloudy when i look under the hood. I do have a fuel pressure gauge installed above the filter and its reading seems to be low. Its about 40-45 and i believe it should be around 60 to start up. I've already:

replaced spark plugs and checked wires

replaced fuel filter:the last time this happened i replaced the filter and it seemed to work, but that was the first change since the car was bought. Its only been less than a year since I changed it out. could there be a clog again that fast?? i only fill in chevron 91 so don't know about that.

replaced fuel pump(255L)

checked fuel pressure regulator (stock) i also have an fmu but from my understanding that comes after the stock one so it should have anything to do with starting up. And don't really know how, all i did was pull the vacuum hose off the top, still no start!

what would you guys recommend on checking next?

I appreciate any help, this has been an on going problem for a while now and its slowly killing me inside!! thanks again guys!!

ok so i decided the to check the fuel filter again and blow it out and put it back and the car starts up fine now. I don't get it? does anyone know what the cause of this maybe. i heard that there can be vapor that gets caught in the line, but it doesn't really get that hot in hawaii and i heard no hissing or noises when i unscrewed the filter. Just wondering any input would be greatly appreciated. thanks again