It sounds like your transmission is slipping. Check the Transmission Fluid. It should be within the allowable range, and blood red. If it's brown or smells burnt, you may have transmission issues.
Harmonic balancer
Trany shot this is usually caused by excessive wear and abuse ( such as reving the engine and dropping it into gear at high rpms) or mileage exeeds mechanical limits. However it has probably been abused!
hey whats up person
Fault with the clutch probably.
Highly-inflated ego.
the transmission is slipping
because someone probably turned the engine on
worn belt or your clutches need to be rebuilt
park it in the garage until you work out what problem you have
Most likely revving due to a dirty/clogged air filter.
The antipollution filter on a 207 peugeot comes as an indicator that the car has to be cleaned by reving it.
throttle plate stuck, accelerator cable binding, vacuum leak, tps malfunctioning.