I've seen so many threads on this lately, and being plagued by the same noise, I've looked into this a little more. What I've found in my case is the steering rack tubes that are pressed into the K member are causing the popping noise. Ford has issued a TSB for this which I'll post along with this.
What I did to temporarily fix this is I sprayed WD-40 on the rack tubes where they butt up against the back side of the K member, behind where the front arm of the "A" arm mounts to the K member. Ta-da no more noise. Unfortunately I know this won't last too long as the wd-40 will wash off next rainstorm and the creak will be back. I took some pics of where to spray the lube, and it really helps if you have a straw to direct the spray. Sorry for the quality, but I was doing this in the dark. Hope this helps anyone with this noise.
And the TSB
TSB
04-24-8 STEERING RACK NOISE
Publication Date: November 22, 2004
FORD: 2002-2004 Mustang
ISSUE:
Some 2002-2004 Mustang vehicles may exhibit a squeak or creak type noise while turning.
ACTION:
Replace the power steering gear tube bracket. Use only replacement parts that have a green paint dot. Torque the fasteners to 52 lb-ft (70 N-m).
PART NUMBER PART NAME
E5DZ-3K620-A Bracket
WARRANTY STATUS:
Eligible Under Provisions Of New Vehicle Limited Warranty Coverage
What I did to temporarily fix this is I sprayed WD-40 on the rack tubes where they butt up against the back side of the K member, behind where the front arm of the "A" arm mounts to the K member. Ta-da no more noise. Unfortunately I know this won't last too long as the wd-40 will wash off next rainstorm and the creak will be back. I took some pics of where to spray the lube, and it really helps if you have a straw to direct the spray. Sorry for the quality, but I was doing this in the dark. Hope this helps anyone with this noise.
And the TSB
TSB
04-24-8 STEERING RACK NOISE
Publication Date: November 22, 2004
FORD: 2002-2004 Mustang
ISSUE:
Some 2002-2004 Mustang vehicles may exhibit a squeak or creak type noise while turning.
ACTION:
Replace the power steering gear tube bracket. Use only replacement parts that have a green paint dot. Torque the fasteners to 52 lb-ft (70 N-m).
PART NUMBER PART NAME
E5DZ-3K620-A Bracket
WARRANTY STATUS:
Eligible Under Provisions Of New Vehicle Limited Warranty Coverage