Again--check all of your vacuum hoses--if they have never been replaced--
replace each and everyone of them--there is a vacuum tree that is located
back behind the throttlebody--it's mounted to the intake manifold---it's held in place with a 10 mill bolt--remove the bolt and the vac tree--there will be about 5 or 6 vacuum hoses going into it--on the vac tree there will be an 0 ring
that seals it to the intake manifold---get some sensor safe permatex gasket maker and glue the sucker back into the manifold and then tighten the 10mm
bolt back to hold it in--let it all set up over night and then crank her up the next day--bet your light won't come back on after that--and you will have spent
less than a 20 to make the fix---oh yeah your also going to feel like the car has more power after that---if you decide you can take it another step
and replace the intake manifold gasket for another 30 bucks and help it even more---vac leaks cause headackes like the one your having--and you can throw money out in directions that won't come close to making the fix. Cheers