boost leak, ignition

hey guys, i got a 1994 laser awd. The car was kinda "stumbling " at higher RPM's. I recently replaced the spark plugs (ngk) and air filter and is still doing the same thing every now and now then. The spark plug wires were replaced about a year ago. It's bad when the car is cold or raining outside. Could it be an ignition problem or a boost leak?; which I haven't checked for yet. Any help would be appreciated.

Could be either, but I'd bank on a boost leak, since your ignition parts are so new. Do a boost leak test per VFAQ.com.