1993 Lexus LS 400 loss of power

I was driving around a interstate ramp and when I got to the interstate lost power by the time I got off on the next exit there was smoke coming out from the back of the motor and there was barely any acceleration the car ran perfect before this just had a tune up check the fuel pressure checked the cats check the ECU check the coils there is no check engine light I can't think of anything else to check also checked the mass airflow sensor all of which were not the problem im Stumped led to believe that might be something electrical if everyone can help me out it would be greatly appreciated