bad idle and "random misfire" code

[FordDesignGuru]

2001 ES 2.0 with 100,000 miles
new plugs, plug wires a year old.

It is running rough at idle and AC will stall it.
As idle drops to 600 rpms the brake booster goes weak and brakes go hard - to be expected?

I am tempted to change plug wires again... can't find a vacuum leak but they are hard to find.

Where should I look first? I am NOT a mechanic... lol

THANKS in advance

[njintau_fsd]

Check your brake booster line, and VTCS if you have them. I suspect its the brake booster line actually, its the vacuum hose that starts at the brake master cylinder and ends at the crank case/Intake manifold. A good way to check for vac leaks is, when the cars running, mist some wd-40 around the vac hoses. If the car's idle changes, then the hose you sprayed the wd-40 on is the culprit.

[FordDesignGuru]

UPDATE
We checked all the vacuum lines, the injectors, the coil pack, and my mechanic said heck it just does not run right even above idle.
He said he could hear the tensioner flaking out (!). I couldn't.
He pulled the valve cover and sure enough, the blasted belt had jumped a tooth. 100,140miles. I bought the car at 58k miles and do not know if the belt had ever been replaced. I think not. I didn't think belts would jump a tooth. Mechanic said the tensioner gets old and when the car is started on a hill and rolls back a bit the belt will go loose and jump when started. dang.

Are ebay timing belt kits ok? cnsautoparts?

[FordDesignGuru]

When doing the post mort on the timing belt we found that the tensioner spring was stretched out - a $5 item that is NOT included in the timing belt kits and had to go to dealer to get a new one.

The tensioner spring was the weak link here and was responsible for the belt jumping a tooth.

When they say you need to change timing belt at 105k mi - believe them! I have 101k miles on the car now.

Also found that the EGR was plugged and sticking. That's pretty common.

[meGrimlock]

i think it depends on what kit you buy. the big-daddy kits with everything (usually sold for around $300+) will have them. my timing belt was changed by the dealer last year. i asked for new spring for peace of mind but i didnt see this $5 part on the invoice...good to know for future reference.