My 94 civic had overheated and so my brother replaced my water pump, tensioner, couple hoses and timing belt. Seemed to be fine until a couple days later it started hesitating when I started it and when I'm driving sometimes hesitates and while idling at a light or my drive way it feels like its struggling to stay on and almost feels like its gonna die. It does it less in neutral or in park. What would cause this?

 

Y was it overheated?
did he bleed the coolant correctly?

 

many possibilities here. your brother could have the mechanical timing off a few teeth, there could have been engine damage from the overheat. have him run a compression test, and also verify the timing is correct.