I picked up a 1994 Mercury Sable here in Hawaii with 50320 original miles for $450 everything on the car is like new all records are in the car and was well Maintained the engines runs like a top a 3.0 the problem is the trans shifts fine goes into all gears and does not slip not even a bit when the car is below normal operating temp. As soon as it hits the L on Normal on the temp gauge it will not shift into reverse at all giving a false Neutral in reverse and in drive you have to rev it to exactly 2500 RPM to get it to engage into drive once that happens it will drive forward all day no slipping and shift between the gears until you stop and again it has to come up to 2500 to engage the forward gear. As well when you shift it into Reverse at operating temp you will feel the soft clunk as it engages reverse then hit the gas and it just spins. again Cold below operating temp reverse engages right away and pulls strong no slipping so do all the forward gears this only happens when the car is at the operating temp literally as soon as the temp gauge touches the L on normal. and the forward gears engage exactly at 2500 with no deviation. I have changed fluid and filter with no change have ran Sea Foam trans cleaner through the system no change, have added a bottle of Lucas with no change. Anybody have any ideas? I have a hard time believing the trans is shot or the converter or the valve body is bad considering cold it shifts out fine. and normal temp is where the problem is. I even disconnected the temp gauge for a sec to see if I could fool the ECU or Trans sensors into think the car was always cold but didn't change anything. Does anyone have any experience with this issue? Any Help would be greatly appreciated. I know traditionally trannies going bad they are worse when cold and then better warmed up as the fluid expands this one has me a bit confused.