Welcome to the Catera forum.
I can help with the MAP sensor, as your best bet is used parts. I replaced one on my 97 Catera, used
http://car-part.com/ and paid only $45.00 and added $17 to warranty the part for 2 years. Didn't have a problem with it. eBay and car-part.com are the best place to get quality used Catera parts.
Never experienced the other problem with the 2, 4, 6 block