Good to hear you are keeping up on the maintenance. Check the fuel pressure, low fuel pressure will give you the symptoms you describe. If you do not have a fuel pressure tester most parts stores like AutoZone, Advance, etc have a tool rental program.
A restriction in the fuel system will also present like this, look for kinked lines, hoses or a damaged fuel rail.
Clogged fuel injectors are also a possiblity, but they usually do not clog all at once and ususally give you a miss fire code (generally cylinder specific)
also check the fuel pressure regulator.
It still sounds fuel related to me but one other possibility is the PCM is recieving signals from the oxygen sensors that the system is running lean so it is sending more fuel to the engine than it needs. It would give you a very sluggish acceleration and poor idle because the engine would be operating "flooded".
Symptoms of this would be a drop in fuel economy and if very severe the oil may have a fuel smell and the plugs, when pulled, would have a black appearance and a raw fuel smell. Normally the system would catch this & give you an oxygen sensor code but have seen it happen without the o2 failure code. It ended up being corrupted data in the PCM. Not saying this is your problem but if all the above fuel issues come back ok, this would be the next step I would take.
A lot of info, I put it in order of probability.
Let me know if it helps or you have any questions.
Monday, August 31st, 2009 AT 7:46 PM