Haven't heard about an acoustic CD, but I do know his new album's due out around early June (I think it's June 2nd in the US and June 9th in the UK or something). Here's a nice article on it;
Elvis Costello - new album & 2009 Tour Dates (Beacon Theatre, Count Basie, Telluride & Bonnaroo) - BrooklynVegan
I take it the 80s sound you're referring to is on his Punch the Clock and Goodbye Cruel World albums? Because if so, you're right, those albums do suck.