I have an 88 Ford Taurus that just started acting up again after a couple years, and it only seems to develop an issue when it's cold out. The first thing I noticed when driving to work the other day is that you could feel the car starting to hiccup at around 50 mph. It quit doing that for a couple days then it came back. It was warmer outside the other day and I went to start it so I could move it and it starts, but with a low rough idle. If you gas it a little it starts to smooth out eventually. I was starting to think maybe fuel pump, but you can hear it pump the system up fine. But I am also not sure what the operating pressure of that system is. I checked the pressure the other day and it was reading low 30's, around 32 or 33 psi. It has a fairly new throttle position sensor on it, and I replaced the MAP sensor a couple years ago (they do not run at all without those working correctly). What should I be looking for here?