Why does my 2000 petrol rodeo surging under load and intermittently other times?

Your 2000 petrol Rodeo may be surging under load due to several potential issues, such as a clogged fuel filter, a failing fuel pump, or dirty fuel injectors, which can restrict fuel flow and affect engine performance. Additionally, problems with the ignition system, like worn spark plugs or ignition coils, could cause misfires that lead to surging. Intermittent surging can also be triggered by an air intake issue, such as a dirty mass airflow sensor. It's best to conduct a thorough diagnostic to pinpoint the exact cause.