Chuck,

When was the last tune done ?  Spark plugs, plug wires need replacing,
throttle plate might need cleaning, clogged air filter.  A

Also, I've seen post on TalkaboutAutos pertaining to aftermarket air
filters like the K&N filter that requires oil poured onto the filter to
trap dirt and debris. And after thinking about it,it makes sense that this
oil would blow through to the manifold and cause damage along the way to
intake sensors. So which filter type are you using ?

Scroll thru all the posts under the Z-Car link, lots of useful tips from
folks who have been there and done that.  Good luck.

WB