  We present observations at 1.2 mm with MAMBO-II of a sample of z>~2
radio-intermediate obscured quasars, as well as CO observations of two sources
with the Plateau de Bure Interferometer. Five out of 21 sources (24%) are
detected at a significance of >=3sigma. Stacking all sources leads to a
statistical detection of <S_1.2mm>= 0.96+-0.11 mJy and stacking only the
non-detections also yields a statistical detection, with <S_1.2mm>= 0.51+-0.13
mJy. This corresponds to a typical far-infrared luminosity L_FIR~4x10^12 Lsol.
If the far-infrared luminosity is powered entirely by star-formation, and not
by AGN-heated dust, then the characteristic inferred star-formation rate is
~700 Msol yr-1. This far-infrared luminosity implies a dust mass of
M_dust~3x10^8 Msol. We estimate that such large dust masses on kpc scales can
plausibly cause the obscuration of the quasars. We present dust SEDs for our
sample and derive a mean SED for our sample. This mean SED is not well fitted
by clumpy torus models, unless additional extinction and far-infrared
re-emission due to cool dust are included. There is a hint that the host
galaxies of obscured quasars must have higher far-infrared luminosities and
cool-dust masses and are therefore often found at an earlier evolutionary phase
than those of unobscured quasars. For one source at z=2.767, we detect the
CO(3-2) transition, with S_CO Delta nu=630+-50 mJy km s-1, corresponding to
L_CO(3-2)= 3.2x10^7 Lsol, or L'_CO(3-2)=2.4x10^10 K km s-1 pc2. For another
source at z=4.17, the lack of detection of the CO(4-3) line yields a limit of
L'_CO(4-3)<1x10^10 K km s-1 pc2. Molecular gas masses, gas depletion timescales
and gas-to-dust ratios are estimated (Abridged).
