I have a 94 del sol si (d16z6) and in first and second gear only it "pops" out of gear. no problems just as long as I holding it in gear. could this be the syncronizer in the tranny??

No, What it ussually is when that happens. is that you need to jack the car up, get under neith it and unbolt the exhaust from header to get to the shift lingage and do some tighting and then feel the shifter it should get tight, you want to adjust to the point where theystill flow freely but it not hard to move.