Speedo cuts out and car stall's???

Check/ replace speed sensor. But check wiring /plug first.

In my case of these symptoms, the lights on the dash all illuminated, the speedo needle went to zero and the engine cut out, but almost instantly everything was corrected and the engine ran again. It was due to the engine rocking back on the engine mounts which over time caused a fracture in the rubber connector for the vaccuum pipe to the EGR valve. As the engine rocked back under acceleration so the vacuum was released, the ECU switched everything off, the engine rocked forward, closed the rubber pipe connector crack and the ECU switched the engine back on. I found it as I broke the rubber connector while cleaning inside the inlet manifold and EGR valve with spray solution.