98 LeSabre engine

Hi guys,
Recently have been having bad pickup on acceleration. Changed plugs and no change. Am starting to loose 1/2 gal of anti freeze on long trips. Also starting to see small micro dots of what I think is antifreeze on outside windshild (like its coming from under the hood of the engine compartment) , because it smears and doesnt totally dry. I see no leaking pools of wet under the car.
I am assuming it is the UIM that needs to be changed. Had a shop change it almost 3 years ago, but I'll bet it was replaced with same part and now it is failing again ( changed at 75,000 and an now at 140,000). Can someone give me a rundown of the all the items that will need to be changed in this operation.
For instance: oil, antifreeze, and other parts that are not in the kit for good maintance

Thanks

Sounds like your intake plenum failed again. I would change it with a Dorman brand unit, change the oil and you should be fine. I've done two of them in the past and each took me about 2-3 hours to complete.The parts were under $150.00 including the oil and filter. Do you shop on Ebay? The plenum can be found for a reasonable price if you shop around a little.

The problem was the UIM/LIM. Got the Dorman kit and a GM Aluminum Gasket. Replaced it all and now works fine. The lower gasket was more of a problem than the upper in that it had larger fail areas than the upper. The GM lower gasket cost me $65 at a dealer. This gasket is a huge improvement (nice thick aluminum) over the plastic one it replaces.
Unfortunately I am now an expert at doing this repair. I really think I could do it blindfolded.

I will say that replacing the lower gasket is not an option, it is a must. Those that dont are betting on a losing hand.