I have a 1991 v6 bird. It starts but idles really rough. When the throttle is held open it doesn't Rev to a higher RPM. Any ideas...

 

Fuel pressure comes to mind, followed by bad injectors and possibly a ruptured fuel pressure regulator diaphragm. Check your pressure on the rail. Should be in the low 40's I believe, if lower could be clogged fuel filter or failing fuel pump. Ohm your injectors, Should be between 13-14 range, my bad ones were 6 and 10. Disconnect vacuum hose from FPR, start engine and wait about a minute of two. If fuel comes dribbling out replace the FPR. Good luck.

 

bad cat

 

Can I ask what fpr means

 

Fuel pressure regulator.

 

There's a good possibility that it could be the fuel pump. I've had this happen on my Firebird a few times, and I would always have to change the pump. Just make sure to get a fuel pressure gauge (Autozone or Harbor Freight), and sample the pressure as you try to run the car.