My blazer has217k it's been parked four like 4yrs.4yrs.ago did harmonic balancer fan clutch water pump radiator belt dr.the problem I have too is cracked flywheel and lower intake gasket leak which I haven't been able to fix due to finances.i just put on distributor cap and rotor @cleaned out spark plugs I don't usually start it but I ran it today @its shaking while idling or stop sign like it wants to turn off but doesn't. I know I have to replace o2 sensors too..it's not burning fuel rite either maybe from o2sensor and setting too long.can anyone tell me what could be problem I have 18s on it with nitrous but I've had tires for along time with nitrogen.the engine doesn't shake it's just inside that I feel like maybe it needs universal joint.i want to fix my problems soon but shaking is worrying.