Need vehicle info. Year? Make? Model? Sounds to me like your carb (if you have one) is letting in too much fuel. This is called having a 'lean' fuel/air mixture. When this happens the spark plug has trouble (or in some cases can't) igniting the mixture, and this leads to loss of power, etc. If this is happening in 3 out of 4 cylinders then that seems odd. Check the fuel lines to each cyliner, check your air filter, and re-tune the carb. If you have a modern vehicle you don't have a carb (most likely) and this would be a computer (ECU) problem. Take the vehicle to a mechanic so he can run OBD on it and see if the problem can be fixed. Another, simpler, idea is to try giving it more gas while you shift. Don't redline it but try giving it more power to start with before letting the clutch out. If you are shifting too early (If the engine lugs when the clutch is out) then getting a lean mixure is common. This is the engine trying to stay alive. Try holding it at 2000-2750rpm while shifting, on a flat area, and let the clutch out slowly. If it holds fine, then progressively shift from 1-2 at lower rpms. This is most likely a cheaper way to diagnose it than taking it to a mechanic. Can't help much without that info. Good Luck, Hope this helps