Noises when coming to a Stop

[Bellingham]

So, i have had some vibrations and odd noises/sensations in the front when breaking for a little while. I assumed it was time for some new rotors as i had put a couple long descents under breaking that i figured warped them. Spent the money to get HQ drilled rotors and new brake pads. Breaks feel great now at speed and no vibrations. But...as i get slowed down it sounds like the engine is dying, grumbles a little and i feel some pulsing, not in the break peddle though. Any ideas on this? It never dies and if i baby it to a stop by applying break until i get to low speed then letting off and kinda gentle pumping it to a stop. Engine has 3in intake, new muffler/cat, throttle body spacer, HID lights. Those are the only mods i can think of that would affect this, but HID, Intake, throttle spacer have all been on for a long time and this has only been happening for about 2 months. Any ideas/suggestions are appreciate, Thanks!

[Mudderoy]

So, i have had some vibrations and odd noises/sensations in the front when breaking for a little while. I assumed it was time for some new rotors as i had put a couple long descents under breaking that i figured warped them. Spent the money to get HQ drilled rotors and new brake pads. Breaks feel great now at speed and no vibrations. But...as i get slowed down it sounds like the engine is dying, grumbles a little and i feel some pulsing, not in the break peddle though. Any ideas on this? It never dies and if i baby it to a stop by applying break until i get to low speed then letting off and kinda gentle pumping it to a stop. Engine has 3in intake, new muffler/cat, throttle body spacer, HID lights. Those are the only mods i can think of that would affect this, but HID, Intake, throttle spacer have all been on for a long time and this has only been happening for about 2 months. Any ideas/suggestions are appreciate, Thanks!

Do you have an erratic idle? Throttle Position Sensor comes to mind. Also have you tried cleaning the throttle body, IAH and TPS? Any whistling noises like a vacuum leak?

[Bellingham]

No, idle is very smoothe. I took the throttle body off when i added the spacer and cleaned all the residue off the fin and areas i could reach on intake manifold. What is the IAH? and how do you clean the Throttle position sensor? I hear no vaccum leaks, have a slight leak in the exhaust manifold, but i was able to weld that up pretty good. I also forgot to mention i have one of those resistor chips that is spliced into the wiring by the throttle body, forget the three letter abbreviation for what wire it comes off of but it is to improve milage. Thanks for the help!

[Mudderoy]

No, idle is very smoothe. I took the throttle body off when i added the spacer and cleaned all the residue off the fin and areas i could reach on intake manifold. What is the IAH? and how do you clean the Throttle position sensor? I hear no vaccum leaks, have a slight leak in the exhaust manifold, but i was able to weld that up pretty good. I also forgot to mention i have one of those resistor chips that is spliced into the wiring by the throttle body, forget the three letter abbreviation for what wire it comes off of but it is to improve milage. Thanks for the help!

I always do that IAC, IAH is the Houston Airport, lol.

Would that be the MAP sensor you are talking about?

Hmmmm if it was a carburetor I would think you may be running low on fuel and when you stop it stops spraying as the fuel moves forward. Might be worth having a look at the fuel pressure on the rail even though it's fuel injected. Really strange problem. I tell you what I'm just grabbing straws here, let the experts weigh in. One will be along pretty soon.

[Cheromaniac]

What is the IAH?

I also forgot to mention i have one of those resistor chips that is spliced into the wiring by the throttle body, forget the three letter abbreviation for what wire it comes off of but it is to improve mileage.

I think he meant the IAC (Idle air control) valve that sits in a little "barrel" on the side of the throttle body. Just undo the two Torx screws that hold it in place, remove it, and clean that plus the inside of the barrel thoroughly. This valve allows some air to bypass the throttle blade when it's shut so that the engine doesn't stall when you come to a stop. If it's dirty it can stick and not function as it should.
The resistor chip that you mentioned is for the IAT (Intake Air Temperature) sensor, and it's meant to fool the engine computer into thinking that the air inside the intake manifold is cooler than it really is. The computer responds with a slight enrichment of the air/fuel mixture and a slight advancement of the ignition timing, so you might see a slight improvement in performance. As for gas mileage, it does diddly squat.

[olds-cool]

My first thought was the IAC too. I used to have a Lebaron that would die at stop signs and it shuddered a bit before doing it. I'll bet the IAC is gummed up just a little bit and causing it to react slowly. It's a free fix as long as you have some carb cleaner around and if it doesn't take care of the problem, well it sure didn't hurt it.