#4 cylinder leaning out

[hpmachine]

Gotta little prob. sr20det red top/ top feed fuel rail/ greddy intake/ 740cc injectors... pulled the plugs to do a compression test (which turned out perfect across the board but noticed that my #4 spark plug was white as ghost!! fuel pressure gauge is reading about 35 and all the other plugs are a nice tan color. at idle I also heard a very faint hiss (of Air??) by this injector. I'm thinking it's either not sealing correctly, maybe not enough fuel pressure or perhaps clogged injector? any input??? thanks

[bonifade]

do a cyclinder leakage test and open the rad cap if bubbles come out of there it's ur head gasket. also another way to check see if ur exhaust has white smoke that has a sweet smell to it if it does then again this confirmes ur head gasket is bad.