Cadillac Forum - Enthusiast forums for Cadillac Owners

I have a 1995 Cadillac Eldorado today i went on about a 7 mile drive and noticed it was starting to overheat when i got a message on the display saying Engine Coolant Hot which switched to Idle Engine then back. I happened to be only about a mile from a friends so i stopped there and waited an hour or so for the engine to cool i then went and checked the coolant level which was just fine and then proceeded to check all fluids while i was at it. On my way home a drove for a total of about five minutes and the coolant temp. had gone from 88degrees to 250degrees triggering this message i decided i would drive home from that point at about 35mph after about 5 miles i got another message with the previous two telling me Engine Overheated then Stop Engine. I noticed that if i put the car in neutral the engine seemed fine but as soon as i put it back in drive the car shuddered violently and almost stalled i was only a mile from home so i limped home at 25 noticing the car would not let me accelerate which im guessing is probably a computerized safety for when the engine overheats when i got home i checked the codes via the on board diagnostics and the only codes i have are P056 which ive had since i purchased the car in may which i do believe is for a transmission speed sensor and P069 which is new and i have not been able to find any referance to this P069 code so im trying to figure out what is going on with my car and where i should start im thinking that replacing the thermostat would be a good starting spot but i am not sure thanks in advance for any help.