A simple engine performance check is the injector balance test. A balance test might help us determine which cylinders are causing our engine driveability concerns.
The idea behind a balance test is to measure engine RPM while unplugging individual fuel injectors to see how each injector affects performance. This is similar to an ignition balance test which involves shorting a cylinder with an engine analyzer. And unlike pulling off spark plug wires with the engine running, disabling injectors keeps us further away from high voltage secondary ignition wires.
To perform an injector balance test:
1) Attach a tachometer to measure engine RPM
2) Bring engine to normal operating temperature
3) Unplug the idle speed motor or idle speed control valve
4) Disconnect the harness from one injector
5) Measure engine RPM drop
6) Reconnect the injector harness, and repeat this for each individual cylinder
A problem cylinder will show little or no RPM drop when the injector is unplugged, which would warrent further testing at that cylinder.