93 stx issues

[Redneckryder]

My truck has issues, that I am aware of. It's the issues that it just recently started having that annoy me. The vibration at low speed that goes away when I push in the clutch...the tires setting their own air pressure....that kind of stuff. The big one is this: 4.0, 5 speed, 4x4. When I take off, it falls on it's face...stumbles a bit, then it clears up, and it takes off like a bat outta hell. Some days are worse than others, some days it lasts longer than others. When it comes online, there is enough power to go from coughing and sputtering, to lighting up both rear tires, much to the landlord's dismay....

I have just replaced the plug and wires, and went completely ape shit on the throttle body with carb cleaner. It's real purdy now. Still don't run worth a damn tho....Any ideas? I searched, didn't find anything that sounded like the same thing

 

[94Reborn]

How does it idle? You could pull the vacuum hose off the fuel pressure regulator and see if fuel comes out. If the reg has failed you could be dumping a lot of extra fuel into the cylinders, which would make it run lousy until its able to ignite the increased amount of fuel.

 

[armadillon]

Vibration: How low is low speed for the vibration? Also, is this RPM related or speed related? Big issue: You say "when I take off", do you mean you start the truck and take off? or do you mean you're idling, warmed up, and you give it a little throttle and it stumbles?

 

[Redneckryder]

How does it idle? You could pull the vacuum hose off the fuel pressure regulator and see if fuel comes out. If the reg has failed you could be dumping a lot of extra fuel into the cylinders, which would make it run lousy until its able to ignite the increased amount of fuel.

It idles like crap...sounds like it's missing and gonna die. Free rev and it runs great, under load, falls on it's face. Where is the FPR?

Vibration: How low is low speed for the vibration? Also, is this RPM related or speed related? Big issue: You say "when I take off", do you mean you start the truck and take off? or do you mean you're idling, warmed up, and you give it a little throttle and it stumbles?

Vibration: When I take off, probably 5-10 mph it starts. Continues on until it feels like stopping. Sometimes 35 ish, sometimes 60. The heavier the load, the higher mph it goes into. Big issue: always when cold, sometimes when warm, not so much when running for over 45 minutes.

 

[94Reborn]

If you can rev the motor from idle without problems its probably not the fpr. I would think you'd have bad running conditions all the time. But its on the passenger side of the motor just below the upper intake, bolted to the fuel rail. Google a picture and you'll find it no problem. The vacuum hose plugs right into it. It could also be as simple as a clogged fuel filter. As for the poor idle, the idle air control valve is always a good place to start, you can clean it with maf or electric parts cleaner. Its bolted to the upper intake manifold.