My car has developed a hesitation/slight miss between 1k-2krpms when under load. It doesn't miss if its just idling, only when driving it. Sometimes the SES light comes on but I don't think its related to the hesitation problem. Had new plugs and plug wires put in about 10 months ago. Where should be the first place I look to find out whats wrong with it? If I floor it from take off it will sputter and hesitate very badly, seems like the more gas you give it the worse it gets, until you get to higher rpms. Also it backfired once.

 

You must be able to read codes at least if you can't grab actual real time data.

Be sure you don't have a dead cylinder first. You can do it with an IR thermometer on the exhaust manifold or use a timing light.

If that appears ok, then try disconnecting and plugging the vac line to the EGR valve.

Last, if that appears ok, then try monitoring the fuel pressure during the problem.

 

that discription matched my situation exactly when my opti started going.