I have a '94 Mustang with the 3.8 engine that was rebuilt 25 000 miles ago. Idles smooth, starts great and has no hesitation. Everything is as it should be. A month ago I filled it at a gas station I usually don't go to and after about 1/8 of a tank being burned the check engine light came on. I checked all the hoses, wires, basically everything I could put my hands on and it all seems ok. I disconnected the battery and reset the computer and it was fine. A few days ago I again filled the tank at the same station because it was the only one open locally and the next day the check engine light again came on. I thought maybe it's some bad gas or something similar. Then the next day when I started the car a huge cloud of white smoke came out the back for about 5 seconds or so. I know white smoke usually means water and coolant is being burned but the coolant level is up and hasn't dropped one bit. I'm not losing oil, coolant or anything. I even took out the MAF sensor and sprayed it a couple of time with an electrical contact cleaner I bought specifically for electronics and contacts. It looked like new before and after I sprayed it, not covered in any gunk at all. My guess is water in the tank but I'm not too good at troubleshooting this kind of stuff.
I'm taking it into a garage to get the diagnostics read but I was wondering if anyone has any ideas what it could be.
Thanks for any and all input or ideas!