Three problems

1. Oil leaks out of the crankshaft oil seal. Oil seal is new. A sleeve installed over the harmonic balancer. :screwy:

2. Power loss and vent blows hot air going uphill.

3. Idle rich.

1990 G10 4.3L V6 with 170,000 miles.

HELP!

1. Oil leaks out of the crankshaft oil seal. Oil seal is new. A sleeve installed over the harmonic balancer. :screwy:

2. Power loss and vent blows hot air going uphill.

3. Idle rich.

1990 G10 4.3L V6 with 170,000 miles.

HELP!
Best guess..
#1 bad seal or bad installation. Possible damage to sealing surface.

#2 & #3 vacuum leak. Check all vac lines.

FWIW
YMMV