Caribbean Smart car

I have a 2010 smart car that I shipped it to a Caribbean Island. After it has been on the island for less than 4 months it has now started to miss and hesitate. One time it wouldn't even keep idling..... the weird thing is the check engine light has still NOT come on. (1 month ago I put some injector cleaner in the gas) And when it does idle...I step on the gas and it only rev's up to 3500rpm...is that normal? and what do I check if the check engine light doesn't come on?