GMC Repair: power, gmc safari, gas filter

Question
I own a 1996 GMC Safari 2 wheel drive 4.3 liter. My wife noticed a slipping or chugging feeling while on the freeway. I replaced her vehicle with mine and drove hers. I didn't notice anything except for a louder exaust (I did notice a leak by the converter). Two days later it was raining and I drove the van and noticed a severe power loss, but could not tell if it was the motor or the tranny. The problem started to go away when the van warmed up. Any ideas?

Thank You, Dean

Answer
hello Dean
this sounds like should have the excaust fixed  it will louse back pressier the the catlaic converter and when was the last time u did a really good tune up and wires also and gas filter . it would do the trick it is not the tranny pete so rest your mind pete