Truck does not start in the afternoon and stalls.

Hello folks,

I have a 2000 ML 320. Has done around 80K miles on it. Still have the OE battery :-)

A few weeks ago, my wife drove the car and left the lights on and as a result drained the battery.

Got a jump start and started the car, but after that have been facing a weird problem.

When I try to start the car in the afternoon, it just cranks but does not start. This goes on for 10 sometimes 15 minutes and then it starts. A few days ago, the car suddenly just stopped right as I was driving it. Fortunately, I was on city streets and I could pull over to one side. After that the car has stalled at least a few times - it seems that everytime the car has stalled ( 4 times so far) I was slowing down either at an intersection or to take a turn.

Reading some of the posts on the forum, I have started believing that it must be the CPS. But on one post I read that an Oxygen sensor could also cause similar problems as can a bad fuel pump. Can anyone recommend a way to find out if it is one or the other?

Also, how easy is it to replace the CPS? Does a certified mechanic have to do it or can I just get the part and change it myself? I am quite handy with tools - but in no way an experienced mechanic.

Any inputs, comments, feedback wil be highly appreciated.

Thanks.