My 89 crewcab dropped about 6 mpg over night. I just installed my rebuilt 454 and was averaging about 12mpg now I'm down to a little over 6mpg. It dumps way too much fuel at idle especially when cold. It dumps so much fuel it fills up the throttle bores. I tried buying an aldl cable and using win aldl but can only pull up maw/ip, prom a and the iac. The iac is jumping from 7 to 256. Would like to be able to see O2 and map at least. Any suggestions?