No the problem is caused by 1 of 4 things, but is most notably the first one.
Replace the Spark plug wires, and the spark plugs. Fouled or incorrectly gapped plugs will cause backfires like crazy. Also poor sparking wires will most certainly cause backfiring problems. I practically replaced and rebuilt the whole darn engine, before realizing that I hadn't replaced the wires ever.
Also the intake manifold and air cleaner may need to be cleaned out. Often the gunk built up inside the intake manifold can cause the system to be leaky via the vaccuum seals of the valves. This is not loads of fun to do, but can be done, and requires someone with knowledge of tools to remove the various components and get at the internal parts of the upper intake manifold to wash out the upper valves with carb cleaner spray, and paper towels.
Lastly you could have a vaccuum leak. Those are most fun to diagnose as you need to listen for a hissing sound. One or more of the hoses connected under the manifold may be disconnected. These hoses are not usually made out of the best material in the world, and may have become cracked, broken, or don't hold a good seal. Replacing them can be a bear, because often times there isn't a cheaply made replacement available. But use your best judgment and the people at Home Depot/Lowe's/Autozone may be able to help.
check pcv hose elbow for vacuum leak.
In my 03 mercury sable, I had the same problem and it was the PVC elbow hose. It had a huge hole in it and I saw online that this is a problem with the 24V sable.
A bad crankshaft sensor can have several symptoms. The engine could stall, backfire, be sluggish or not run at all.
Your Mercury Cougar might stall in reverse because of a problem with a bad crank sensor. This problem could also be due to the crank sensor wires which are damaged or not wired correctly.
Check fuel pressure.
timing chain or distributer --or gypsies, gremlins etc.......
Replace your IAC Valve-No more stalling
check your idle air control valve
Idle could possibly be too low.
The stalling could be caused by several things. The egr valve could be clogged, or there could be a sensor problem among other things. Clean the egr valve first, then check the computer codes for possible problems.
If it stalls at idle or when slowing down, it could be a fuel filter. Or it could be the ignition control module.
It sounds like some sort of lean condition. Perhaps a vacuum leak? Plugged fuel filter?
If the car is starving for fuel or air (low power at idle), the car will stall while turning.
Alternator is not making enough power.
The power brake vacuum booster is failing.
NO Emission control only, does not affect performance.
pressure relief valve isn't working properly
The power brake booster is bad.
Have your mechanic or the dealer check out the sensor. I own a 2001 Santa Fe and it happened to me a couple of times and they changed it for free. It was under Warranty.
Look for a hole in the PCV valve hose on the backside of the engine.
There are several reasons an engine may stall while driving, here are three.The fuel tank is empty and the engine is starved of fuel.Not enough power to climb a hill causing a stall.Faulty or damp electronics on a petrol engine can also cause a stall.