2002 chevy cavalier

yes, i own a 2002 chevy cavalier and when i start up the engine will miss for approx 30 seconds and then runs smooth only when it is cold. does anyone what the problem is and where to start at.
thanks

SES light on? If so read codes- could be as easy as a fouled spark plug. Or you can run some injector cleaner in your next tank of fuel- I've had that fix my issue.....

Are you losing coolant or is the engine overheating?

It could be coolant in the cylinder(s), from a failed head gasket, burning off on a cold start....

is there a test to see if it is a leak head gasket? thanks for the help

First on a cold engine, top off coolant if needed...

Next run vehicle to normal operating temp.......shut off......safely remove radiator cap(if no rad cap, remove the reservoir pressure cap)......you will need a pressure tester, with a special adapter to attach to the reservoir, if there is no radiator cap......pressurize system system overnight.....testers can be borrowed from places like AutoZone.....

Next day, remove spark plugs, disable fuel and ignition(remove fuses or disconnect harnesses)......have someone crank over vehicle and watch spark plug holes....if coolant comes out, you found your problem....