5.0 idles poorly

[ARCA44]

I have a 1992 Mustang 5.0 that I bought cheap to put the motor in my 77 Bronco. The car will die at idle untill it warms up. After warming up it will barel idle as it is poor. I have checked the idle air by pass sensor. Electricall it works, and I cleaned it out good. No luck, only sligthly better performance.

Car saat for about 2 years and supposedely the gas tank was only siphoned out and soem new gas put in, however it still smells bad.

will bad gas make it idle rough and then perk up wihen the throttle is pressed, Engine runs much better at higher RPM

 

[TX '73]

My dads farm truck sat for a long time. It ran rough and would idle like crap for a long while. It was even hard to start sometimes. We ran it long enough to cycle some new gasoline in there and it runs much better now. I would try 10 gallons or so and run it and see if it gets better. You can also be thinking about fuel filter and injectors. Your problem sounds like old/bad gas to me...just my 2 cents.

 

[09163x]

Definatley run some clean fuel and maybe dump a can of Sea Foam in the gas too. When are you planning to swap motors? I just pulled a 5.0 from a 90 f-150 for my 72....not sure when I'll get it installed.

 

[Scodge]

The alternator on my '87 mustang went out a few years ago, and I noticed that when I replaced it, all the loping idle and stalling problems went away. They eventually came back, but I think the new alternator with a solid voltage signal helped. When you drop the mustang motor into the bronco, I recommend picking up a wiring harness at fordfuelinjection.com. Ryan makes a wiring harness that is a work of art, and my 92 engine started up and ran like new after I'd hooked it all up. It's a little pricey, but worth every penny.