marryson

I have posted this before but i thought I fixed the problem..... so here i am again. my car would hesitate (Rock back and forth) when accelerating below 2000rpm. This started happening when my coolants were leaking and I was driving for 10-20 minutes without even knowing about it. when I got home, there was light smoke coming out of the engine somewhere. when I fix the leak and replace my coolant, everything is fine except for the hesitation issue. I changed my spark plug but that didnt help. any ideas ??