1995 Grand Cherokee Inline 6 cyl?

I changed the exhaust/intake gasket after getting the exhaust manifold fixed for crack. Starts, runs rough, dies. I think it might be a vac leak or O2 sensor. Ran it with leak for some months. The gasket was Fel-Pro. Was a kind of cardboard material. Which I thought was somewhat weak for application. Any thoughts / help ? Thanks.