Getting a check engine light on a 97 NA Olds 88 LS, series 2 3800..

the code is p0108 - manifold absolute pressure circuit high input

I recently replaced upper intake plenum and gaskets, and also decided to plug the coolant lines to the throttle body (between lower n upper intake plenum) and also plugged the EGR port at the lower intake..

Thinking that the code was tripped by the plugged EGR, I bought an EGR block off plate from zzperformance.com which blocks the EGR at the exhaust and is supposed to not throw any codes..

still getting code P0108.. engine runs fine though..

What else should i check? is it possible the MAP sensor went bad? or would blocking the coolant lines to the throttle body cause this? also i cleaned out the throttle body
with brake parts cleaner when i had it out out of the car too..

thanks in advance for any help!!

When you cleaned the T/B did first remove the MAP? If not, this might be why the code is being set.