Engine 5.0 Running Rough (1990)


New Member
Apr 28, 2019
Lancaster, CA
Mustang running very rough Any Help Greatly Appreciated.
i did upgrade to 24lb injectors but problem was there prior to the change as well
changed : distributor cap and rotor, also change the coil, spark plugs + wires, fuel filter, fuel pump, IAC, EGR,

still can't figure out the problem. also noticed the EGR + smog items dont have vacuum lines. could that be the issue?
also need help with a full diagram of the vacuum lines (preferably a video)

also runs really rocky/rough on step of the pedal may be due to stretched throttle cable but was running like so before it became stretched, could it be a block in the exhaust such as a catalytic converter? as that bottom piece of metal did shave off at one point (car is pretty low) i ask because it pops on deceleration and if i revv it (or try too shall i say) it also pops it sounds likes its coming from underneath me/exhaust area.
  • Sponsors(?)

General karthief

wonder how much it would cost to ship you a pair
Mod Dude
Aug 25, 2016
polk county florida
I kinda giggled at the screen name, cool.
Ok, first thing you can do is check for codes. Here is a link to a 'surging idle checklist' that will help you, start at the top and do it step by step.
Don't skip around, each step is dependent on the result of the step before. It has a diagram for the vacuum line too.
Is there any modifications other than the injectors? I hope you saved the 19 lb injectors.