I have a 98' Volvo S70 and it keeps turning off after I initially start it. It shakes a little and basically turns off and this arrow light and sometimes the oil light comes on. I have to put the car in park and then restart it. It's usually fine after this but will occur again later in the day if I've left the car parked for several hours. Can anyone tell me what can be causing this? I've had a mechanic look at it and he replaced something that he thought was the problem and it still keeps happening.

take to a repair shop as sounds like the inhibitor switch may be causing an issue but could also be a few other things , get the OBD codes read and go from there

There should be a little notch on each cam gear that lines up with a notch on each side of the cam cover.
Try looking at it from the side and rotating the engine with a large ratchet on the crank bolt (turn clockwise only).

The timing marks will line up every TWO rotations. You'll see how the notch on intake and exhaust cam gears both line up with the notches on the plastic cover.

There is unfortunately no "trick" for this. You will need the service light reset tool. On some other Volvo models it was possible to reset the light by holding down the reset button for the trip meter and turning the key to position II - keep holding the reset button down for about 30 seconds.

Brake light comes on auto each time you start the car (saftey check) and will go off when you press brake pedal.

Blinking arrow will stop when you click seat belt together (driver)

turn ign off press key in towards drive stem and turn anti clock (5degs)and pull out

Put in key hold in mileage reset button and turn key to on (dont start the car )the last click before starting (and keep finger on miles reset button till flashing stops
then turn off ,this resets all service lights,
tc

i don't know what it means but sometimes if you turn the car off, allow it to cool down, then turn it on and let it sit for about 10-15 mins before you drive it the arrow goes away... i hope that helps...

If you do not have the code. look in owners manual some times it is written in there or there is a card with code on it. if not you need to go to a volvo dealer and they can get the code for you. You may have to pay them for it.

It should come on for a few seconds with the other lights, but should not stay on for a minute.  If you get an intermittent ABS light it could be a speed sensor or more likely the ABS module.  If you get an ABS light along with a flashing arrow light, traction control light, or  speedometer and odometer goes out, then it is just about guaranteed to be an ABS module issue.  There are online sites that will rebuild ABS units for around $150 or less.  They are pretty easy to remove and install yourself with the right socket.  Google "Victor Rocha".  His site has good information on the procedure and he is well trusted for his rebuilding jobs (I have no affiliation to him or the site).

Something is going on with the transmission control system. You need to find out what codes are stored in the system. Most likely the transmission range switch is failing.

You need a new ignition switch. They can be keyed to the same key for a few extra dollars.

If the air pump system is setting a fault, then the check valve is probably bad. If it is not addressed, eventually exhaust gases can run back through the air hose to the air filter housing and destroy the MAF sensor, causing these types of problems.

The fuel pump also fails and is a more likely cause of the stalling, and it wont set a code.