[shorod]

Welcome to the forum! To help identify where you should next spend your time and money, you'll want to do some troubleshooting rather than shot-gunning of parts. You need to determine if this is a cylinder misfire, low fuel pressure, vacuum leak, or other. If you have access to a scan tool with datastream mode, you might be able to learn a lot about where you should be focusing your effort.

For example, with the scan tool you'll be able to review diagnostic codes, both current and pending. Just because the Check Engine light is not on does not mean there are no available diagnostic codes. The issue may just not be bad enough to trigger the light. Also, monitoring the Short Term Fuel Trim (STFT) and Long Term Fuel Trim (LTFT) parameters might help you determine if the issue is more likely to be an ignition related misfire, fuel related, or vacuum related.

While you're looking for a scan tool, you could pick up a can of Mass Air Flow Sensor (MAFS) Cleaner and the appropriate security Torx bit, then clean the MAF sensor on your car to see if that helps. Carefully inspect the intake air tubing while doing this, especially where the clamps connect it to the MAF sensor and throttle body and also in the accordion folds.

Checking vacuum at idle with a vacuum gauge could help determine if there's a vacuum leak, but with a misfire vacuum readings can be a bit tricky as well.

If you can get your hands on a fuel pressure tester you can check the fuel pressure at the fuel rail during Key On Engine Off (KOEO) as well as Key On Engine Running (KOER). The KOEO results could help you identify a sticking fuel injector and the KOER results could help you identify if the fuel pump, fuel pressure regulator, and fuel filter are doing their jobs.

-Rod