Hi, guys , thanks alot.

I had the problem with TP sensor(throttle positioning sensor), and it often turns 'service engine soon'. Would it be a problem?.

It could be related, but I've never seen a bad TPS cause a stall. Usually it'* high or variable idle, and cruise control won't work.

You know you have good oil pressure, so change the sender, and get back to us with the results. We'll take it from there if there'* still problems.

The low oil pressure as Damemorder stated does in fact stall the engine as a safety feature. So, if you have oil pressure (mechanically checked) then replace the oil pressure sending unit.
A bad TPS will cause occasional stalling (I know this from experience as I go through a TPS every year and a bit). Clear the codes and run it for a while until the check engine light comes back on then check it again. If it has the same code you will have to check the signal reference (5volts) the signal (0.4 volts or close at idle) and ground from the TPS sensor while connected and running hot. I put a paper clip in from behind the plug (through the rubber seal) into the plug until it contacts the wire connector inside. That way I can get the reading without damaging the wire by poking it. Run it at idle nice and hot while checking it for any wierd spikes in the signal (0.4 volts idle to 4.8 or so volts Wide open throttle (not while running!))

I replaced the oil pressure sender today morning, but the gauge is not stable..
Once the engine is warmed up, and whenever I hit the brakes, the gauge drops down.

Any idea ?. ....

i have that same prob did u drop the oil pan??