Cadillac Repair Questions? Ask a Mechanic for Answers ASAP
did you check for vacuum leaks? did you check fuel pressure? theses generally point to a lean condition
Check the intake manifold plenum boot. These can leak and are hard to find.
The intake manifold has to be removed to access the plenum duct/hose, with this repair you will replace the intake gaskets also. This is a 2-3 hr job.
here is a picture of the location