a little stutter shutter
Recently when I turn the ST on I have noticed the rpms fluctuate a little before settling down near the 1. However, sometimes the engine will stutter a little and will continue to do so until I apply a little more gas. I thought it could be IAC valve not cleaned out. So I cleaned it an put applied some oil to it. Thought that did it, seemed to run better and everything. But then just yesterday I started it up and the little shutter happened again? Any thoughts?? Considered running the seafoam stuff but I had just ran some through the vacuum last month. Also thought the PVC might be getting old.

I double check my brake vacuum hose to see if it was leaking or losing suction and everything appears to be ok with it. might go ahead and replace the pvc valve just.

Mine goes through the open loop (when you first start it and it revs up to 1200 - 1400 rpm) and ones everything checks out the rpms drop back to around 600 - 800 (close loop).

Now from what I'm told (by my cousin the ford mechanic and others owners) the ST's have always had a bit of a 'sputter' when at idle.

So it sounds like thats what you're feeling. My cuz said that you shouldn't run 'fuel system' cleaners because it eats the seals on the injectors. But my step-dad dumped a bottle of seafoam in the gas tank in this truck and well...it worked wonders for him.

But my problem is when in gear, foot on the brake if I give it just enough gas to bring the rpms up to 800/900 then let off real quick, the engine with stall.

So who knows, it very well could be the IAC valve. I've never even heard of one until 3 months ago. And I ended up replacing the one on pops ranger two days after learning about them lol.