I bought this truck from a coworker with just under 200k miles on the clock. The truck was used mostly for highway commuting and probably never towed anything in it's life despite being equipped with the tow package. It was her company truck and got most all of it's service at a Dodge dealer. As the truck had a lot of miles I figured some maintenance was due and changed both trans filters and refilled with the last two quarts of Mopar ATF+4 Walmart had on the shelf and the balance with Valvoline Synthetic ATF+4. Before changing the trans fluid it shifted fine with no apparent issues at all. After changing the fluid and filters the truck developed a problem of not going into gear and occasional engine stalling. I found the suction filter was not seated in the trans case which allowed air to be sucked in. In fact when the trans was cold you could see bubbles on the dipstick. I believe the stalling was due to the idle speed control not keeping up with the load changes from the erratic transmission operation. After changing the suction filter again the engagement problem was completely resolved and the occasional stalling problem also appeared to be gone. The stalling problem has since resurfaced. It's as if the torque converter clutch is partially engaging and loading the engine down to the point where it will stall. Some times the idle speed control will catch it before it stalls and I can feel the truck try to push through the brakes somewhat. Shifting into neutral at a stop keeps the engine from stalling. Once the trans is warmed up even a little the problem disappears. One thought is that the Valvoline ATF+4 is more viscous especially when cold and is somehow affecting the torque converter clutch. My fear is that the TCC is going to fail and cause other damage when it does. TCC operation when warm appears normal. I can watch the tachometer and see that the TCC does lock up as the RPM goes down slightly during TCC engagement. The TCC also does not appear to slip either. When I last replaced the suction filter I bought a brand new drain pan to save the nearly new fluid so the Valvoline Synthetic ATF+4 is still present. My next move is to drop the transmission pan a 3rd time and replace the fluid with Mopar ATF+4. Has anyone else experienced such symptoms? Anyone have any other issues with Valvoline Synthetic ATF+4? I just hate to think that I would have been better off not doing preventative maintenance.