Rover 200 jerking/coughing through the gears

I have a Rover 200 1.6 Manual 1999. Few months ago i noticed it was missing/jerking/coughing slightly through the gears (but wasn't too bad). So i put in new set of spark plugs. This didn't make any difference, and so couple of weeks later I put in new spark plug leads, this also did not make any difference. After several weeks I put in a new distributor cap. After putting this in, i noticed the missing/jerking/coughing through the gears became a lot worse and continuous, and it also at times cut off completely when i'd be at traffic lights, and so i'd had to give it more gas to try and stop this from happening. Finally, just recently, i put in new oil filter, air filter and fuel filter. Still there is no diffrerence to its current condition of continuous missing/jerking/coughing through the gears, and at times cutting off at traffic lights. The only time it seems to be driving normal is on the motorway. Please help, any advice?