My 98 Silverado 1500 2wd auto 5.7 liter has started shuddering while driving down the road, it started showing up between 65-75 but now it’s more like 55-75. This problem developed 2 weeks ago. From what I’ve read it seems like it may need a rebuild. The fluid level is good haven’t lost any and when I shift it down to 3rd it will run fine without any problems or shudders. The only other thing I have noticed so far is a fair amount of roll back when going into park and the driveshaft will turn a few degrees while in park on level ground. The engine also has a slight shake while in idle not like a misfire but still noticeable. Any ideas would be helpful.