After the car has gotten out of it's cold start high idle routine, the car will start to hesitate. It's not constant though. Here is the best way that I can describe it. At idle, in Neutral or in gear the car will all of a sudden drop rpm and the computer seems to compensate for it right away by revving it a bit, then it returns to normal. This sometimes repeats 2 or 3 times in a row pretty rapidly and then it's fine for the next 30 seconds to a minute then repeats. So it seems like the car is hiccuping or something. Prior to a few weeks ago, this problem presented itself only at idle. Accelerating and at speed were fine. Then, it started affecting acceleratoin once in awhile in that the car would bog down when accelerating from a stop, but not all the time. One time it sounded like it back-fired when it bogged down. So I changed the spark-plugs and the bogging down seem to have disappeared for awhile, but the hesitation I described earlier still remains. The spark plug tips were very light brown in color. I just did the rotor as well. I kept the old distributor cap cause it was pretty new, but the problem still exists. I didn't do the wires because they are only about 5,000 miles old, if that. The distributor had been replaced about 10 to 15,000 miles ago so I didn't think it could be that. I also replaced the fuel filter, but still no luck.
The car has an automatic and has 180,000 miles on it. The problem does not seem to be affected by weather.
Could it be the fuel pump? Wouldn't that tend to go completely dead though? Any help would be appreciated.