On vehicles with catalytic converters, poor performance can quite often be due to excessive exhaust back pressure. This is usually the result of a clogged catalytic converter or rear muffler. Don't spend hours diagnosing a performance problem without eliminating this possibility. Kit includes test hose with gauge and special adapter for the oxygen sensor fitting. Test can be performed in less than 10 minutes.
Generally speaking, more than 1.25 psi of backpressure at idle, or more than 3 psi at 2,000 rpm tells you there's an exhaust restriction.
This tool can be used at the upstream O2 sensor port, just above the catalytic converter. Remove the O2 sensor, secure it away from any moving parts, then install the gauge. This will trigger a check engine light, but it should clear itself after the sensor is re-installed and driven a few miles.