Low idle/low speed shutter
 

I just replaced the lower left Idler pulley (as labeled on the serp. belt map under hood) because it siezed up with metal shards in the bearings. I replaced the pulley and the belt, which ended up allowing the engine to run.

Now, however, when I start up and shift to drive, everything is ok until i start turning. At low speeds/low rpm, the steering wheel shutters through a turn. it does not shutter at high speed/higher rpm, mainly just idling. Any thoughts? Im thinking to check the power steering fluid, but other than that, no clue. while i replaced the pulley and belt, i made sure all the other pulleys and components (alternator, A/C compressor, power steering) rotated smoothly, and all did. thanks for the help.

Serpentine belt tension? Allways go back a ask what changed. Maybe belt is slipping.

belt tension
 

by the way, it is a 96 4D 2WD 5.0 V8....I replaced the serpentine belt and pulley myself, and thought to have tensioned it properly. How would I tighten if all I do is rotate to loosen/release to tighten the tensioner? much appreciated.

I don't know the spec off hand. Your repair manual should tell you. In general, if you can twist the belt 90 degrees at the longest free span, you have it right. Any more, it's too loose.

I agree, might be a slipping belt, there should be a belt gauge on the tensioner. Have you looked at it?

Might be idling too slow also. Should be an emmisions sticker under the hood, with the idle speed.

belt tensioner
 

Thanks for the ideas, ill check after i get out of work...on the other hand, been reading about air in the power steering fluid could cause shuttering at low speed/idle turning...could this be the problem? I wouldnt think so since before i replaced the pulley/belt there was no problem but im not the one to ask...thanks again

Update
 

Just for an update to whoever else reads this, I ended up being able to stop the shuddering after driving in circles with no throttle and turning the wheel all the way left, all the way right, and doing that a couple times. It has not shuddered yet since doing that. Thanks for all the help and ideas.

If you operate the steering without the pump running (as you would if the belt got thrown off) it pushes fluid up and sucks air into the rack. Ford says to apply vacuum (not from the engine) with an adapter to the top of the power steering pump, where you pour in the fluid...

But i've found that if you hold RPM at 2500, and steer the wheels lock to lock about 20-30 times, it will do just as well.

Good luck!