I recenty had a rebuilt D5 convertor installed about a month ago. It has been working fine under normal driving conditions. However, last night I added some xylene and drove it pretty hard. After a few hard pulls this is what was happening. Going about 40-45mph in Drive and giving it just enough gas to kick it down into 2nd, there would be a pause or a bog or something, and then "BAM", it would hit 2nd gear really hard! Also ater coming off the highway cruising around 70mph and coming almost to a stop, then started to accellerate normally, it felt like I was in 4th gear in a standard transmission. (Bog, bog, bog) What is this? Thanks, R.B.