Changed intake gasket, now it won't start

First of all this can't be from changing the intake gasket. Unless you did something like left a rag or something stuffed in side the intake when you are cleaning it? Without being there I'm just at a loss for ideas on how your motor could be running ok before the intake gasket and then running worse after fixing the intake leaks. Unless the car was Tune with intake leaks? IF it was me I'd be taking the motor out but I'm not suggesting you do that but just saying if it was me....