engine shaking
 

i have a 2000 blazer 4.3LT, V6, 4DR, 2WD an i blew my intake gasket and after replacing it my engine started shaking it wasn't shaking before replacing the intake gasket i've been told that it could be

1.major tune up (i've done plugs and air filter i have plug wires and fuel filter to do)

2. since we had to replace the intake gasket it mested up the fuel injectors an that it needs to be replaced

3. i have a dead cylinders or possibly more than one

can anyone help me out to figure out why its shaking

Thank you