rm125 wont stay running

Hey guys here is the story I recently bought a 1994 Rm125 that needed the water pump seal replaced cause it was mixing water and oil. That is were the fun began once I started I found all kinds of things wrong but meh. Now I have the bike back together and have been trying to start I am getting fuel air and spark and it started once but I have no power the bike seems to be starving for fuel. Once I hit high rpm's it runs better. But here is the issue after getting it running I tried adjusting the carb and seemed to make it worse so I put it back to the original position then tried it again. When I went to take off the bike took off very slow like I needed to push to keep it going and then died now it wont start I can crank or push but it just back fires and then does nothing it is also bumping fuel out the carb bowl overflow. Any help would make things allot easier thanks