OK my 91 Vert tends to have an unsteady idle and surges and feels liek it wants to die form time to time while setting at idle either in park or in drive with the brake in.
It has had a bottle of fuel injector cleaner ran through it, changed the fuel filter afterwards. Has new Cap and rotor, plugs look good (they are split fire though... going to put Autolites in it eventually) they are just slightly black, but no buildup on them. Clean air filter, fresh oil change.
So... whats next? I checked the basics... aslo it tends to sometimes stumbles when you first put your foot into it. Ideas anyone?
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2006 Mustang GT in Torch Red
C&L Intake, Evolution Performance Tune, Borla Axle Backs, Hurst Shifter, 4.10's, JBA Long Tubes, Prothane Engine Mounts, Steeda UDPs, FRPP Charge Motion Delete Plates
I'm having the same problem, put new plugs, wires, cap, rotor, filter oil and fuel, oil change. My car is a 1988 GT..
anyone have any help whatis wrong??
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" The Gorilla fisted carburetor King "
Car 1: 1988 Ford Bronco Full Size.... All Stock
Car 3: 1988 Mustang LX - Drag Car
Car 3: 1988 Mustang GT - Mod's
Front Mod's strangs 10way adj., New ushing,Springs
Rear Mod's Built 8.8" 31 splines, c-clips, 50/50 shocks, 3.90 gears, eaton posi, Engine Mods' Cold air intake..
Bets Time: 14.62
check for codes. i just went thru this. after being able to run codes....the charge air temp sensor was bad. but you wont know until you run codes.
xs
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89 5.0 convertable..paxton 6lb., flowmasters, full police strobe package,dual alternators w/second complete charging system, competition audio system w/18 speakers incuding
4-15" subs in a lexan enclosure
lowered and custom painted with a mustang airbrushed on the hood.
yes, the codes are grouped into two types: continuous and dynamic. you can have codes from errors in the past that will show up in the computers memory. Also, not all codes trigger the Check Engine light
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89' GT Ragtop.
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Ford Racing "C" springs
SLP Loudmouths
Summit o/r x-pipe
BBK equal length headers
BBK strut tower brace
Chipped by DynoSources
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Check codes first! It never hurts to clean your idle air control valve with throttle body cleaner, mass air flow meter with electronic contact cleaner, throttlebody with throttlebody cleaner, replace pcv valve and double check your throttle position sensor voltage.
some codes will pop up during a running test of the motor....this is the best way to start to trouble shoot your enging. let it tell you what is wrong.
if you went to a doctor and didnt tell him what was wrong, how would he be able to treat you? so "doc" pull some codes!
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89 5.0 convertable..paxton 6lb., flowmasters, full police strobe package,dual alternators w/second complete charging system, competition audio system w/18 speakers incuding
4-15" subs in a lexan enclosure
lowered and custom painted with a mustang airbrushed on the hood.
Your post is word for word what my 91 Gt is doing! When I have the throttle half way down it breaks up and surges. I read the post about the TP valve, Im going to try that next. Hope you figure it out.
Scan those badboys! All you need is a short piece of wire and the "check engine" light.
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1992 Deep Emerald Green Mustang GT Hatch, 5 speed, 2.73s, Mac fenderwell cold air intake, '93 Cobra MAF, Mac 70mm throttle body & spacer, Explorer intakes, Mac unequal headers & offroad pipe, Magnaflow catback, Walbro 110lph fuel pump, Jet adjustable FPR, MSD Blaster coil, Accel 8mm wires, FRPP aluminum quadrant, UPR firewall adjuster, stock cable, Granatelli upper control arms.
Waiting to go on: Granatelli lower control arms, and GT40 Iron heads!
Engine Surge and Unsteady Idle. 
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