Recently purchased 99 silverado w/ 160k and was chasing a low power prob. starting at 2000 rpm. Did new plugs, wires, andfuel filter with no change. Was told it could be plugged converters due to high mileage. Ordered a set today. In the meantime a techtold me it could alsobe the MAF. A couple of weeks ago I removed the screen to improve the flow, not paying any attention to the sensors.The techlet let me borrowone from a low mileage 04 w/ 40,000 k to tryand I could not believe the difference in theappearance and power! Mine was totally black, the sensors looked like littleglobs of black silicon,and the supports were black as well. I didn't realize how dirty it was till I saw the 04's. Everything was silver including the sensor. Bought a can of contact cleaner and used the whole can along with a couple of Q tips to (carefully) remove what the cleaner wouldn't. Reinstalled it and now it hauls. Was surprised at having so much trouble without an engine code. It makes sense though, more air is passing over the sensor now that it is clean. I gotta call early enough in the morning to cancel that converter I ordered.
This seems like it should be something to check every year or so especially with the oil type air filters.

 

Thanks for the tip! Gonna check mine tomorrow.