alrite well im new to this board, and totaly new to working on mustang problems. i have a 2004 v6 all stock (for now) with about 78k miles. when im in first there is a kind of winding or whining sound (kind of a wewewewe) that disappears if i take it out of gear. also when im accelerating from around 30 to 50 mph there is a random lag, like it misses a beat. any help here would be great thank you.

 

Auto or manual?

 

oh sorry its a 5spd

 

With the info provided its hard to say anything. My tranny makes noise in 1st gear as well especially since I installed a short throw shifter as it has no sound deading material like the stocker does in it.

 

Very true. If I had to take a wild, random guess based on info provided, I would say it might be in the clutch/flywheel.