O.K, you said in your first post that it had a misfire, seeing as it's a 16v Renault that'll be caused by one of the pencil coils, they're always packing up, best changed as a set, but that's up to you? A misfire will affect the gearbox operation.
Next is to look at the turbine speed sensor fault, best to remove multiplug on 'box & ECU to check connections first, if they look clean & not corroded then move onto checking the sensor, from memory this is fitted into the underside of the 'box (?), the resistance across the terminals should be 300 ohms +or- 40 ohms at 20oC, you can check this at the sensor plug & then at the ECU plug across terminals 45 & 46, if the resistance of the sensor is out of spec then you'll need a new 1, if it's o.k then see if the resistance varies between the 2 points, if so then you've got a dicky connection.
Hope this helps?