Ford Focus engine speed rises on its own

Car starts up and idles ok. When starting a journey pulls away ok then when pull up at junction and dip clutch, engine races up to 4k on its own, falls back and does it again, then does settle down. Next junction or q etc same thing happens. I googled problem which indicated Throttle Position Sensor failure. I fitted replacement this morning but no difference. Can't see any split or broken pipes. Happens same whether on or lpg or petrol. Any ideas please?