Follow up per my previous Transmission post: Have driven approx. 100 miles. since previous post. Transmission would not up-shift out of 1st gear. Parked it for a week. Drove again about two (2) miles and all seems fine...for now. At 341K miles I know a future rebuild is in store, however could a shift solenoid be suspect? In the meantime, what's the wisest plan of attack? Thanks!