Ok Heres the story, the truck runs really rough backfires when you apply gas and then eventually stalls out. When a computer was hooked up to it it was showing no misfires. Fuel pressure at 'ignition on' is good and fuel pressure running is at 60psi. New catalytic converter, recent tune up, brand new distributor. I dont know what else to diagnose
Please any help would be great thanks

 

New cat? Check your exhaust and make sure EVERYTHING is tight-start at the exhaust manifold and go all the way to the muffler. You may be having an issue with no back-pressure. I had this issue with a truck I used to have. A bolt kept coming loose and it would start backfiring on me.

 

Are you sure that the timing is proper?

 

check the timing and maybe a cylinder leakdown test to ensure that the valves are seating

 

I recently bought this truck to so i dont kno the history. I just checked the cat and it looks brand new and checked the rest of the exhaust so i dont think theres a problem with the exhaust. My fuel pressure is at 50psi with the ignition 'on'. Chiltons says it should be 55-64psi with ignition 'on' engine off. Would the 5psi im missing cause all this?
Thanks to everyone who has replied

How would I check the timing?

 

A little update. I ran a vacuum test. Turned out my vacuum lines were shot! BUT after replacing all of them i did obtain proper vacuum with the acception of the gauge reading in the red, "ignition timing problem". I use to have a cam sensor code and a crank sensor code. I replaced the crank sensor and distributor. Now i have only a pending crank sensor code. The engine still wants to stall out, the fuel pressure is good. Its an 01 can the timing be adjusted? The distributor is brand new like i said.
Please any advice would help out a great deal.

 

I know this post is kinda old, but in case you still need help I would suggest replacing your Engine Coolant Temperature Sensor. It's about $10 for a new one, and it's fairly easy to do.

Remove the entire air intake assembly. I unscrewed it at the air box, removed the wing nut thing where it connects to the throttle body, and disconnected the wiring to the IAT and MAF sensors. Pull the wire harness off the rubber keepers on the intake boot and pull the whole air intake off at once.

Pull the thick wire harness out of the way and use bungee cords or zip ties to attach it to the A/C compressor or somewhere else where it won't keep you from turning a wrench.

Some people say to drain the coolant level down below the sensor before you start, but I think the easiest way to do this is just remove the sensor and let the coolant drain down on its own. I placed a catch pan under the exhaust manifold inside of the driver's side front tire and moved it exactly under the drips once the coolant started flowing.

Remove the electrical connector and tuck it out of the way behind the fuel lines or something. I removed the old sensor using a 19mm crow's foot wrench attached to a 3/8" ratchet with no extension.

Unscrew it, let the coolant drain down, put in the new sensor once the coolant stops flowing (threadlocker should already be on the sensor from the factory), hand tighten with your fingers, then tighten it down as much as possible with the crow's foot wrench. You may be able to use a crescent wrench but the valve cover might get in the way. I don't have a wrench in that size, so I don't know.

Re-attach everything, top off your radiator with fresh coolant and you'll be done. The coolant that dripped on the exhaust will smoke off when you restart the engine.

I think this is a very commonly overlooked item when people have issues with stalling/stumbling/running rough. Admittedly, it was one of the last things I replaced after chasing all of the "sexy" solutions like ICM, EGR, IAC, fuel injectors, et cetera. As I understand it, if your ECT sensor isn't working correctly it will affect everything from engine timing to your air/fuel mixture to your EGR.

Anyway, this item costs just a little more than a spark plug and can be replaced in about the same amount of time.

Hope this helps.

2001 Blazer
2dr, 2wd