91 firebird 3.1 runs for 10-15 seconds then dies. Replaced fuel pump and filter. was told that it was crank sensor. pulled harmonic balancer and there is not one. Was also told it could be cam position sensor but there is no listing in any parts store for this part?? What could it bee. please help, ready to blow this thing up.

 

No crank or cam sensor. Maybe stop listening to whoever is telling you this stuff. Give some details about the engine. All original? Replacement parts? Don't just keep buying stuff until you know what's wrong so you need to do some diagnostics. Need to check for vacuum leaks. Fuel pressure. Injectors. Fuel pressure regulator etc. etc. It would be good to have a manual (Chiltons is good enough) so you can see where things are and it lists some tests you can perform. Start with vac leaks. Then smell for gas in the vac line that goes to the fuel pressure regulator. Check the passageways in the idle air control valve (IAC) are clear. Check the IAC moves (it's what controls the idle). Then check the injector resistance. If they are original it's likely they need to be or should be replaced. If you don't have a digital volt meter that can also measure resistance then get one. They are fairly cheap and really very useful. Then see where you are.