That Guy

So my car started sttutering yesterday and I took it to the dealership. The way it was running it felt like it wasn't getting enough gas. I could feather it and it would run smooth, anything more than that and it would stutter. It even stubled when it was at idle. Out of gear is when it would rev the smoothest. At the dealership they said it was the air intake (Roush). Basicly they didn't want to touch it and claimed they couldn't because the intake was aftermarket. When I told them that the intake was purchased at the dealership where I bought the car in Michigan and they put it on for me he didn't know what to say. They sent me on my way after charging me $200 for the 30.000 mile tune up. I turned left out the parking lot and it died on me at the light. I got it started and went to work. I called the guy up and told him what happened and he said that he would have a guy that could look at it on Friday. The guys in my install bay and I pulled the T tap in the fuel line to see if there was a blockage, there wasn't. We cycled the ignition a couple of times and very little gas would come out (low fuel pressure). The only thing we can think of is that the fuel pump is going bad. Is there anything else you guys think it could be?

JewStangGT

sounds like fuel pressure...this may be a dumb question...but when did u last clean the filter on the roush intake?

monkeydude3

check your fuel pressure to be sure, then check the intake and inspect the MAF. it may be dirty, and WILL CAUSE that problem

That Guy

I cleaned the filter less than three months ago. Could a dirty MAF really cause this problem? The wiered thing was is that it just happened while I was driving down the street. I came out the parking lot and it started stuttering a half mile down the road. It just got worse the whole way home. If the fuel cut off switch was tripped it wouldn't flow fuel at all correct?

That Guy

The car only has 30k miles on it

mustang_montana

sounds intake related to me. ive had the same issues dozens of times for a dozen different intake issues. definetly check over all that stuff first, your problem is very common in mustangs it seems. sooner or later it happens to the best of us. ill just list some things that caused sputtering/surging or dying at the light for me.

exhaust leak at header to midpipe gasket (before the front o2 sensor) caused sputtering/surging.
vacuum leak caused searching idle, and rpm dive at idle
dirty iac valve caused rough idle for me, but commonly will cause the car to die at idle, or when comming to stop.
tb butterfly open a hair at idle (caused high idle and deceleration issues)
tps, i replaced mine but its known to cause issues like yours when it goes bad or needs to be recalibrated
egr valve, havent replaced mine yet but an easy way to check is plug up its vacuum line.
fouled o2 sensor (front) or any leak before fron o2 sensors
discrepency in tune
leak on intake after maf

those are what gave me trouble, i wouldnt put any money on it being your fuel pump. low pressure could just be a dirty fuel filter or bad reading. ill put money on it being intake/vacuum related or a tiny exhaust leak before you passenger side o2 sensor. keep us updated though. theres a huge thread about this issue, and troubleshooting it, on a different forum (MD) and i think we should start a similar one.

That Guy

Today we'll pull all the intake stuff apart and clean and reassemble it. I'll let you guys know if it works after that. What's a TPS?

*storminnorman*

had the same thing on a 99 after 2 fuel pumps (the ford ealer did that) it still cut off . i bleed the fuel line and for 2 weeks and 300 miles it runs great.