1.8t idle problem

[mazdatech60]

i have an 02 beetle 1.8 turbo.
it has an idle problem/misfire type issue.
at idle it hunts between 400-600 rpm very quickly.
at a steady cruise it misses a beat every now and then under very light load.
it has set sevral different codes.
p0300
p0301
p0302
a lean code, and a throtttle postion code.
i cleaned the throttle body, no help.
i monitored the throttle position with my scan tool, it read 5% @ idle and as i gave it more throttle, dropped to 0% then went up as normal.
i replaced the throttle body with a new vw part and fixes the t/p code.
but it still idles bad.
i have checked the cam timing/installed new belt, new vw plugs, and checked for vacuum leaks real well.
the fuel trims show it is adding alot of fuel, but it runs like its lean.
are there any issues with o2 sensors?
the car is a 5 speed with 122k miles, all stock.
thanks in advance for any help you can give.
kris sherer.

p.s. i almost forgot, i have been a gm tech for 7 years and worked for mazda for 2 as a tech, so if you need to get technical thats ok

[mazdatech60]

exact codes are............
p1176
p0300-0304
p3211

[veedubmechanic]

Look under the intake manifold at the pcv breather lines coming off the block. There is about 500.00 worth of breather lines/vacuum hoses that are very very prone to cracking because they are thin and brittle. If you smell the oil vapors by the intake manifold you problably need new ones.

[mazdatech60]

i checked the lines, no vac leaks.
i disconnected the lines at the manifold and plugged them to be sure.
same problem.
i can tell its running lean, and i installed a new vw o2 sensor to eliminate that.
it actually runs better but its still not correct.
unstable idle, slight misfire at cruising speed.

[mazdatech60]

ok, it seems like the turbo is boosting at idle.
you can feel pulses through the vacuum port. should there be boost at idle?

[veedubmechanic]

u replaced the maf sensor yet? Supprised it would last 122k miles

[mazdatech60]

no, i cleaned it.
i have disconnected it while running and it made no difference.
is that normal?

[mazdatech60]

does anyone know 100% where the timing marks should line up?
i have checked it twice. i line up the cam with the notch up top.
and it looks like you can see a notch on the crank pulley that lines with a little spot. is that right?

[91celicaFB]

replace maf and see whats up