I have a 2004 blazer wit a 4.3 engine.Blazer would run then after sitting for 2 days will not start.Backfires thru throttle body while trying to start. Have replaced crankshaft sensor,camshaft position sensor and the icm. Blazer still backfires and won't start.Anyone have any ideas.

 

Could be a problem with the distributor cap & rotor, plug wires, or low fuel pressure. These things don't play nice with aftermarket caps & rotors, use AC Delco. Have you checked fuel pressure and leakdown? https://blazerforum.com/forum/2nd-ge...eakdown-88305/