A Middle East-based amine sweetening unit, with an overall capacity of about 2.2 BSCFD of gas, is among the world's largest process plants and currently processes sour gas with 10mol% of hydrogen sulfide (H2S) and carbon dioxide (CO2) put together. Current expectation is that acid gas contents in the feed may increase beyond the design limit of the plant. The present work is an effort to quantify the effects of the feed gas CO2 increase on the plant and to proffer solutions to handle these effects efficiently. We revised the kinetics of amine-based CO2 absorption correlation of an existing model using real-data-driven parameters re-estimation. Evolutionary technique that employs particle swarm optimization algorithm is used for this purpose. The new CO2 kinetic model is inserted in a first-principle process simulator, ProMax (R) V4.0, in order to analyze various solutions necessary to mitigate the operational challenges due to increased feed CO2. The process plant with present design and operating conditions is determined to handle up to 8.45mol% CO2 contents in the sour gas feed. Further results revealed that methyldiethanolamine, diethanolamine, and dimethyl ether propylene glycol (DEPG) could not handle this high feed CO2 challenge, even at maximum (design) steam and solvent usage. However, diglycolamine exclusively renders the solution as it treats high CO2 feed gas efficiently with allowable utility consumption, while satisfying the constraints imposed by product gas specifications.