Long story short, car sat for 3 years because we didnt know what happened, turns out I had coolant leak into the throttle body and that made me have to replace the whole throttle body assembly (throttle body, tps, iacv,) and repair the ecm and replace the blown eccs fuse. Now that I have gotten it to start again I am having issues with it. When it idles it will go from 750rpm to 500rpm every 10-15 seconds. When it drops to 500rpm for a seconds it makes a strange squeaky sound. When driving the car, once i get to around 1800rpm, it shudders and wont shift. What could the problem be!!

By the way, MAF is clean