So what's the deal? I'm having trouble with my '98 F150 4X4 (4.6, 4R70). It shudders almost like an engine skip but only in 3rd gear. Just replaced the plugs at 100,000, still does it. We use Tauruses at work for company cars and it seems like one of them has always got tranny problems (not that my co-workers are easy on stuff). Another guy I know has a Taurus and its doing the same thing my truck is doing and only in 3rd gear. Heluva coincidence? I baby my truck and rarely tow with it. If I punch it, it shifts and acts normal but when I'm puttering along at 30-ish mph it does its thing.

Any thoughts out there? Thanks

mine does it to (used to), only thing i can think of is that the OD is trying to kick but engage firm enough because of either the vavle arent letting enough fluid by,or there is a vac leak causing to not shift all the way in, i borrowed a buddies s-chips, and it hiked the shift pressure up and it shifts great now

You sure your plug wires and coil packs are good? Have you flushed the tranny fluid?