I have a 1994 Mercury Grand Marquis, has roughly 80,000 miles on it (odometer is broken). In the past 4 months it has developed a very odd problem:

If the engine is stone cold, and you try it accelerate you are not able to. The engine will sputter and go "rewwwww *silence* rewwww *silence* as if it is trying to die. If you idle, it is fine, but the moment you try to give it the slightest amount of gas, it does this. It does this for about 1/16th of a mile before allowing full acceleration, and the sputtering goes away.

Why does it do this? I've cleaned the MAF sensor and I can't remove the IAC (it's screwed in too tight) to clean it (but i assume it is not the IAC as I idle fine).

 

Not sure if this is the same problem/solution but my 85 needs to idle for about 2 minuets before the motor smooths out to a nice smooth idle. In my case, the O2 sensor needs about 2 minuets to heat up from the exhaust gasses before a measuring reading is available to the computer, which then trims the gas/air mixture to proper ratios (called the "run" mode). This happens even in 80 F weather when the car is started after a half hour of sitting. Once the sensor produces between .4 - .6 volts DC, that voltage is sent to the computer to tell it to switch to "run" mode. While the sensor is heating up, the computer runs in the "limp" mode. So maybe a dead O2 sensor?