Car Dies After Driving A While. Help Diagnose


something stupid will fall out of my mouth
Founding Member
Jul 21, 2000
Tulsa, OK
Ok.. Here goes. I just got the car and don’t know its history. Things I have replaced are coil packs, charcoal canister lines and TPS. Otherwise the car is nearly stock. did clean the MAF sensor, IAC and ran codes. Only Rear 0/2 codes and one EVAP code. Nothing else out of the ordinary. Just a 97 GT 4.6L 5 Speed with Gears, Off Road H and a K&N. Otherwise Stock.

Right now it fires up and drives fine. I can drive it 15 or 20 miles to work in the morning no problems. I can drive it to to the store or wherever else without incident however if I get it on the highway for sustained driving and then get off the highway and pull up to a stop light I am taking my chances. Seems like half the time I will pull up to the light, push in the clutch and it will come down to idle, then drop about a hundred rpms and then drop a couple of hundred more till it gets down to about 400 and it acts like it is wanting to die and sometimes does but mostly just sits and stumbles. If you push the gas it does nothing but kill it quicker or you get a slight pop like a intake backfire or just nothing. Will not gain RPM and if it does die and you try to re fire it will just crank and crank and then sometime fire and still stumble and not take fuel and then randomly out of nowhere it will finally hit and you can keep your foot in it and and limp it a little ways to park it and it seems to have all of its power back while it is doing that. But if you let it die or try to go too far you will be right back where you were with it stumbling and dying. Now if you let the car cool down for a little while it will fire up and driving fine again till you drive it a while. It acts like something is getting hot. I just cant keep throwing money at it trying to fix the problem when there are no codes really and nothing to go by. Oh and when it does It doesn’t seem too rich, I don’t have that really strong fuel odor but I do smell fuel.

Some things I have noticed are this. Yesterday the battery light has started to flicker sometimes but not necessarily when the engine is running bad. Just while driving along it will flicker a little like it wants to come on steady but never does. Also the rear crossover on the fuel rail has been spliced with a barbed piece of brass that looks like it may be a slight restriction and is laying on top of the EGR pipe. I thought maybe fuel was boiling so I insulated this as good as I could with two layers of rubber heater hose around it. And this morning I noticed my fuel pump sounds kind of high pitched and changes tone when I have the brake on. Not sure this has anything to do with anything. Any help would be appreciated and if you need any additional info just let me know. I will see what I can do.
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Bob Hughes

Dec 26, 2011
Southamptonl, NJ
Maybe someone else will confirm this but I've heard of faulty alternators causing similar symptoms....I know it sounds hard to believe, but may be worth checking if ur getting the battery light.


SN Certified Technician
Aug 14, 2009
Houston Texas
First, check the battery and battery cables. Are they clean and tight?

Have the alternator tested for correct output and excessive AC ripple (bad diode). Most autoparts will do this for free.

Check the fuel pressure intake vacuum reference line. Is it connected and leak free? Are there ANY vacuum leaks? Exhaust leaks?

Now check the IAC.

IMO a problem with a fuel pump would show up under load not only a idle.


New Member
Jun 28, 2011
Mine did something simila. Turned out it was a vacuum leak in the gas tank itself. The gasket on the top Plate of the tank was broken.
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