have you checked the wiring to the Engine ECU there is a modified loom which has a plastic protection instead of a foam coating. they also suffer from the metal anti theft cover rubbing through the loom that can cause random faults. The 1.2 can be a funny b***** for spark plugs as well seen loads of poor running and fault codes caused by NGK plugs, stick to genuine Renault ones

The MAP (Manifold Absolute Pressure) sensor's job is to tell the ECM inlet manifold vacuum. The sensor will either be located directly on the inlet manifold, or it could be fitted on the bulkhead, in which case there will be a small vacuum pipe connected to it from the inlet manifold. If so make sure the vacuum pipe is in good condition and is not split.

A faulty sensor will play havoc with the fuelling and consequently engine running, because the ECM will not be able to correctly determine manifold vacuum, but anyone with a Mityvac tool should be able to test it for correct operation.

As stated above, your problem could well lie elsewhere. Engine misfire, blocked exhaust, worn valve springs, sticking valves, late valve timing, intake air leaks would all have a serious effect on manifold vacuum, and the only way the ECM would know any of this is via the MAP sensor, so make sure you check it and confirm it's at fault before parting with your cash for a new one. Otherwise you'll be wasting your money.