Chevrolet Repair: high idling, fuel consuption, vacuum leak

Question
The idling speed of my engine kept rising during the last weeks. It is now apr. 1500 rpm. fuel consuption is higher then normal. Could the cause be a vacuum leak? How can I detect this? A local dealer told me it was the MAP sensor but replacing it made no difference. Electrical problem? Computer read-out gives back a rich exhaust indication. 88 astro 4.3 V6. I also replaced the oxy sensor.

Answer
Hi Rob, This is a TBI engine right! The TBI gasket on these does go bad and leaves a hole for air to get into and makes for a high idle. I would remove the TBI unit from the truck and clean ALL vacuum passages.The carbon build up is unreal as you will see. You may need to use a piece of wire to do this. A coat hanger could also be needed.

Let me know how you make out

Have a  Nice Day     Mark