Cadillac Seville

I have a 1992 cadillac seville (4.9) liter when ipull off from a stpo it hesitates like it; s not taking the gas, when I let off the gas a ease back on it slowly is goes today I stopped at a light at the bottom off a hill and when I pulled off it stumbled all the way to the top before it would run right I couldnt let off it because it wouldnt made it to the top. Arter it passes this little session it runs fine up to 75-80 mph do you have any seggustions. Also a have a code (io39) someone said it was sevice air ride (is that so) also I have a code (e90) could this be my problem i; ve installed new plugs plug wires distributor cap and rotor button and ignition module andstill have this problem please please help I need this car to go to work also I installed a new ignition coil
August 19, 2006.

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