Need help with 97 Odyssey

okk.. I was just gonna see if anyone on here could help me out.. and tell me what i should do if they know..

okk.. My Honda Odyessy has been sitting up for about a month and I took it to the shop to get the radiator fixed on it and then is sat there about 2 to 3 weeks.. but ever since i got it out of the shopit has been acting like this.. it runs fine if you are on a open road and stuff but when u stop at a red light or something and then u hit the gas to go it just putters along and does have any power... but then it kicks in and runs fine... does anyone have any suggestions for me??? Please!!! Thanks