Z24 Question

[galinamarie]

just replaced head gasket on a 95 chevy cavalier z24, I know the timing is right but when you start the car it runs great for about a minute then boggs down and chokes itself out. I ran a compression test and its fine until it starts to bogg down the compression goes up. I thought maybe it was the cat converter, so i unbolted the exhaust, but it still does it. HELP!!