1999 Pontiac Montanna

You never leave a car running, as it will
overheat the Exhaust Converter
When you run out of fuel, you sometimes
ruin the Fuel Pump
It depends on gas to lubricate it,as strange as it sounds
Check fuel pressure & volume at the motor with a gauge

Has the exhaust ( catalytic converter) been check for proper flow? I would try a test pipe to by-pass converter and see if that helps. You used to be able to buy them, but a good exhaust shop can make one pretty quick, and then try it.

Yes the flashing light means the module did not read the chip in your key as being the right one for the van.
Could be the key, the sensor in the lock cylinder, or the module.

easy this question as its so simple ,look on the air intake and their should be a take off pipe from teh exhaust pipe manifold so warm air is picked up to stop the venturi from freezing in the intake manifold ,either the operating mechanism is broke or the vacumn pipe running to it is perished or the end split ,if you cannot get it sorted make sure the valve flap from this hot pipe is open and block the cold intake pipe off with something that cannot get sucked into the engine

It could be a broken Oil Pump, Is there oil in the engine or when you hit the pothole you could have hit the Exhaust Pipe and broke the pipe causing a Exhaust Leak.

at 150,000 miles pretty much everything could be worn out if it is all original, if the van is in really good shape no dents or bad dings paint good, interior is in really good shape and the van has been serviced on a regular basis then yes fix it, also this is a free wheeling engine so if the timing belt breaks there is no damage to the engine, if it ran good with no excess oil useage or engine noise fix it..

P1483=engine cooling system performance
Are you adding coolant each time this light comes on in the coolant reservoir?
if so,you need to find where it is leaking out,

Ck your exhaust pipe at rear of car noting any obnoxious smell like rottrn eggs. Hold a piece of paper, I use a dollar bill ,in in front of the exhaust. If it blows the paper gently, you have a catalyctic converter going or is bad. Will need replace if so.

If this is a gas engine, check the ignition coil or plug wires. A simple test...

Start the truck at night, then look under the hood while it's running. Don't use a flashlight or your headlights; it should be dark !

If you see sparks anywhere around the engine, you've found the problem. Now you can turn on a light to see where they're coming from - probably from a cracked ignition coil.

Good luck !

Marco

Had the same codes on my truck. cat converter was plugged. I was told to take the cat off and gut it, then put it back on and it would run fine, but that didn't work. You need a new cat. Might want to replace the o2 sensors before and after the cat also. Hope this helps.