Had the exact same symptoms...thought it was due to cracked intake manifold gaskets, so I replaced them. Even though they were cracked & needed replacing, on the first test drive the cel came on & the same codes appeared.
In desperation, I emailed Jerry Lemond, who was gracious enough to reply quickly. He indicated that there was un-metered air entering the system somewhere (vacuum leak) OR the little sensor wires in the MAF might be crudded up with K&N filter oil residue.
After replacing all my cool lookin', but poor sealing, stainless braid vac & brake booster hoses with rubber, I bought a can of MAF cleaner & de-crudded the sensor wires.
Result...cel free for over a year.
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