I know you guys all mean well, but 4800rpm at 80mph is not right. I'm a mitsu master tech ( I work on bmw's now however..more money), and I can tell you from experience that your convertor is not locking up. Could be a number of different things causing it, but that is not right. 70mph should come in at 2500rpm, with 80 at 3500-3800 rpm if the convertor is locked up. ONLY use the mopar atf +4 in your 99. No off brands without an additive to ensure proper clutch enggement in your auto trans. Dex 3, valvoline muti veh, and various others doo not have the proper friction modifier for our trans...you will have lots of problems with alternative fluids. Hope that helps!:)