i put a b18 w/ 25,000 miles on itin my car and just drove it for the first time and the shifter keeps popping out of secon and fourth only,anyone have any ideas what is wrong

 

Is it moving back and forth a lot (under acceleration, tranny braking). I found that mine was getting forced out of gear. Look at the bar connecting to the back of the tranny, there should be a rubber bushing in there (tranny side). If it's worn to hell that's your problem (it could have been made worse & damaged tranny if you let it go too long).