ok last time i try to solve this problem . i have a 1990 fleetwood 4.5 mpi . with the onset of slightly cooler weather (mid 60s' at night ) my car runs smooth once again for a short while . i live in arizona and it has been missing sometimes seemingly as much as three cylinders not working . some of you have tried to help me solve this and everything seemed to point to injectors . well now i am getting a smooth running engine for as long as 15 20 minutes with some sudden change to the miss again but clears out in a few seconds and runs smooth again . this was rare for the whole summer with the heat . the first run in the morning when it was hot resulted in the miss right off . have tried cleaners and different gas . i am somewhat of a mechanic when it comes to cars but fall short on practice with the computerized ones since i dont have access to electronic equipment . i know i could figure it out if i had access to equipment. i need to know if someone can tell me what else could be wrong and how and if an injector could be affected to work correctly under cooler conditions . if i had to make some wild guess i would think temp sensitive component like ecm or ignition module . so any details one of you might have please let me know . i can understand just about anything told to me so make it as technical as you like . this thing is driving me nuts since it is hard for me to work on my car now due to physical problems . also when i punch it down when it is working properly i do get a nice little cloud of black smoke . just the intermittent thing makes it hard for me to believe injectors are the problem . i just want to get it fixed .