I have a 97 Ram 1500. For the last few weeks on my way to work and home on the interstate my truck has been "missing" every onece in a while at 70mph. It was an intermittent problem but alwayd happened aroung 70mph. I started chasing the problem with plugs, wires etc. This morning it missed several times and on the final time it shifted out of overdrive and then back in. Any ideas?? All advice is appreciated. Thanks in advance!!!