2003 Mustang GT issues

westberry23

New Member
Aug 24, 2025
3
0
1
Waco TX
All,

Hello my mustang has had a tick for awhile and we have been narrowing it down, next is the lifters/rockers I need to get on order. But the car just started acting weird but throwing no check engine lights.

Symptoms: Car would feel like it is "skipping" or "running in a dream". And eventually it started dying as the RPMs drop when i pull up to a stop. I removed the exhaust (Fwd of CATs), ran it and still had it die. I am unsure where to go next with no check engine light or obvious signs. Any help is appreciated. Thank you.
 
Welcome to :SN: !

The 4.6L has no lifters, so no worries there. But I have to ask what you mean by "running in a dream"? And you removed the exhaust forward of the cats - meaning you removed the headers/exhaust manifolds? I can only guess you were replacing the gaskets for a suspected exhaust leak? An exhaust leak that is upstream of the O2 sensors can cause a rich condition which might cause the engine to not run well. But I'd guess that there would be a code thrown for that particular issue. This is all a spitball guess from someone who's never really dealt with a 4.6.

I'd suggest listing any mods your car has as well as anything that you can think of that you've done to the car for people to give you their best advice. Pics are always welcomed and can sometimes help if your pic shows anything relevant, so don't hesitate to share them! I'll step out of the way for now, best of luck and I hope you can get it figured out quickly!
 
Welcome to :SN: !

The 4.6L has no lifters, so no worries there. But I have to ask what you mean by "running in a dream"? And you removed the exhaust forward of the cats - meaning you removed the headers/exhaust manifolds? I can only guess you were replacing the gaskets for a suspected exhaust leak? An exhaust leak that is upstream of the O2 sensors can cause a rich condition which might cause the engine to not run well. But I'd guess that there would be a code thrown for that particular issue. This is all a spitball guess from someone who's never really dealt with a 4.6.

I'd suggest listing any mods your car has as well as anything that you can think of that you've done to the car for people to give you their best advice. Pics are always welcomed and can sometimes help if your pic shows anything relevant, so don't hesitate to share them! I'll step out of the way for now, best of luck and I hope you can get it figured out quickly!
Sorry let me clarify some things, I type like everyone knows what I’m thinking sometimes.

1. There was no work done to the car that caused this, it just started running sluggish and eventually dying. We thought it might have been clogged Cats, which all the symptoms lined up, so I disconnected the cats to troubleshoot, and when I ran it I got the same results, no change.

2. Running in a dream is like when you press down on the gas and you know you should be going faster but you are not. It’s super laggy and sluggish in the 3/4/5 gears.

3. There are no lifters in the 4.6? Everyone has been saying the noise I have been having sounds like lifter tick. Interesting. Guess I’ll have to do more reading.

4. Not very many mods I realize now I don’t know as much about my car as I thought. I just have an upgraded throttle body, CAI, and an upgraded exhaust. Most of my upgrades are cosmetic and this was supposed to be a weekend car. Unfortunate circumstances have pushed this to my daily driver for the mean time.

5. For the noise we changed the timing chain and fuel injectors, thought it might have been exhaust related (see note 1). The noise has been there for awhile, the dying is a new symptom.
 
I hooked the exhaust back up and it seems like the dying thing isn’t gonna happen, at least in the 10 minutes I ran it. But I had smoke coming from the RH side and crawled under and it’s coming from the RH side where the cat tube attaches to the header is what I assume.

I have the knock/tick still. I have videos but do not know how to upload them to here. I am going to change the oil and put the quart of additive in while I have the car in the air.

Next time I take it for a spin I’m gonna throw a code thing on it to see if I can get more information.
 
I'm a month late here but I don't see resolution, so I'll add my .02.

RH side as in pass side- there is a dumb gasket on the factory style manifolds/mid pipe that loves to leak and cause a tick. It would likely not cause sluggish issues though.

Does the "ticking" increase with rpm or stay consistent?

Dying when pulling up to a stop indicates possible Idle control motor issues (IAC) (pure speculation on limited info here). Maybe it's gummed up and needs a good cleaning or even replacement. (use throttle body specific cleaner anywhere near the TB). In simplistic terms the in park/neutral sitting still idle table is different than the coming to a stop while rolling down the road idle table (can't think of the term for that one). If it dies while coming to a stop driving, they don't always do it when sitting still not moving in park/nuetral with the brake on.

Dirty throttle body could also be a sluggish issue along with other items like plugs, fuel filter, etc.