95 Jeep Cherokee Has Problems Starting

My Jeep has just under 100K on it and I have been having problems with it starting. It needed a new starter about 6 months ago which I replaced, but for the last couple months it has taken a couple extra seconds of cranking to start, and when it does its kind of a rough start. The last couple days the rough start doesnt completely get the engine running and I have to crank it for up to about 8 seconds and then it barely runs (very low rpm). If its any help, I drive different distances to work every day....if I take the interstate and have to drive a ways back and forth, I dont have any problems. If I am just driving around town stopping at red lights a lot, I have problems first thing in the morning sitting at a red light by my house. While I wait for the light to change, the engine will sputter and then surge after which the check engine light will come on. I have taken my Jeep to auto zone and the o2 sensor code came up. I dont think that this could be causing all of my problems, but am not sure. Maybe a fuel pump? Thanks

My first thought (as usual) is the crankshaft position sensor. There are numerous symptoms, not always the same, but yours are among them. If you have the 4.0 liter that would be my guess.

You could also take a look in the FYI-How To section, that might give you some additional pointers.

The O2 sensor usually fails in a rich setting, causing lowered mpg and a black, wet, deposit in your exhaust from all that gas.

One thing I've noticed with my 4.0's is that turning the switch to the "on" position, and waiting for the fuel pump to stop running[before cranking], helps with the start.

Lastly, how long has it been since you replaced your spark plugs? Cap and rotor? Plug wires? This tune up can make a HUGE difference in how your Jeep runs. If you haven't done these things in the last 30K miles, then I'd be inclined to do them first, before anything else.

I would like to try to add to whats been stated. I would check your fuel filter and injectors. You can remove the fuel rail and turn the engine over to see if they spray evenly, or just clean the crap out of them. The o2 sensor can have a large effect on what goes on with the car so don't underestimate it etc. Good Luck. DRIVE IT LIKE YOU STOLE IT!!!