3.1 Intake Gasket change?

posted here a few weeks ago about my 3.1 running rough. TPS and IAC have been changed (wasted money). car can be started easily, but it wont idle (most of time when cold). when it is running at high way speeds it seems okay, but when slowing down it will go dead, or run very rough when sitting still. Had it scanned and every thing that showed up was checked and is okay. Was told tonite at rod cruise in, that maybe, good chance that the intake manifold gasket was blown. Is this a common problem? Dread the work. I sprayed around the intake with WD but no change. Guess i was not hitting the spot. Any info on changing this gasket other than pay to have it done. I work on rods for fun, but hate doing it out of necessity. Any other ideas on this idle problem welcome.