I have exactly the same problem with my son (he'll be 3 in April) I have our second due in May and mealtimes are a nightmare. I have tried everything from sitting with us at the table to letting him sit on his own in the kitchen. I have to literally turn mealtimes into a game to get him to eat anything, which can take over an hour. He'll also need the toilet every 5 minutes during mealtime.
I am now trying which many people won't agree with, sitting him at his little table in front of the TV watching his favourite programme. He will sit and wolf down his dinner and even ask for more. Then my husband and I eat later. We're all a bit more chilled out and I actually enjoy my food whilst its hot. Its not ideal and not really how I was brought up but for the time being its giving me a break and he's eating all his dinner!
If anyone else has any ideas I'd be grateful to hear them too!!
