Have 98 Dodge Quad cab w/ 318 ci. Installed a transgo shift kit and transmission does not shift properly. It shifts in/out of gear. Replaced valve body to make it stock again. Same shifting problems. Seems like it stuck in 2nd, but then it pops in/ out of gear. It seems like it is searching for the right gear.

make sure the seperator plates and gaskets are properly in place; a backwards seperator plate and gasket will cause "hunting" symptoms.

Thanks for the info. I have found that the speed sensor was shorting out which was causing the shifting problems. I wire leading to the sensor was shorting out against a air cleaner bolt.