2002 volvo /v40 will no start

Pull the vacuum hose off the fuel pressure regulator. If there is any trace of fuel then the regulator is the fault

Spark plugs, plug wires, and fuel filter. Pretty cheap, quick, and generally recommended around 100,000 anyways.

It could need plugs, or something else. Plugs are designed to last 100,000 miles but no guarantee.
Often times stalling is caused by a dirty throttle body or a faulty idle air control valve. I would have a mechanic check the valve and also see if there are any trouble codes stored in the computer.

I usually service Ford family Brands and will try to assist you. Back in 1995 there was a change to longer service life sparkplugs and the elimination of Distributors with Crankshaft sensor firing of the plugs. It really depends on the Manufacturers' idea of when to replace sparkplugs by mileage and the various filters on the engine.

You can install plugs and filters anytime you want; just a matter of prematurely spending money on something you do not need. Air filters 12,000 miles, Sparkplugs 50,000 to 100,000 miles, Serpetine Fan Belt 40,000 to 45,000 miles, Fuel filter 25,000 to 45,000 miles.

Check with Autozone, Advance, or Oreilys for information about Manufacturers specs. Stay on an oil change interval based on your driving habits. Sometimes oil breaks down without higher miles and you need to change by date rather than by use. Clean oil for Winter starts, clean oil for Summer driving. Twice a year is adequate for low mileage. Watch your Antifreeze, it chemically changes after 3 years and loses corrosion inhibitors.

I hope at least some of my suggestions are useful to you.

oil/filter/lube every 3,500 miles synthetic oils every 5,000 miles
tire rotation wheel align check balance every 7500 miles
transmission service every 30,000 miles
air filter gas filter cabin air filter evry 30,000 miles
if engine has a timing belt(rubber substance) replace every 60,000 miles if it has a metal timing chain lasts almost forever
spark plugs should be good for 75,000-100,000 miles before replacing
Spark plug wires every 50,000-60,000 miles approx.
fuel injector flush every 30-40,000 miles approx.

if the pickup strength use to be better, most likely you need to tune up your car. that could mean to replace air filter and spark plugs. and being a 2002, you maybe close to the 100,000 miles, you should consider change the cables that goes to the spark plugs, they go bad around this time.
you can add some seafoam in your gas to help clean the injectors.
you can add some seafoam in the oil, a 100 miles ahead of your next oil change, you help remove sludge from the engine.
you can add some deepcreek thru the air conducts to help clean the crankcase.

Tune Time.
1)new spark plugs properly gapped.
2)new air filter (check every 35000 miles)
3)new fuel filter (every 35000 miles)
4)1 bottle of STP fuel treatment (red bottle) 4x a year.
5) oil and filter change (castrol or another good quality oil every 3-4000 miles.
6)proper air pressure in tires (check every 2 months
7) service transmission every 40000 miles or less.

New oil and filter
8) new plug wires every 80000 miles.

check your owners manuel..if you have none than purchase one.
I would say leave them alone .

Firing order is 1-3-4-2 (Please rate me if this helps)

sorry but if you think the plugs are wrong then you are a sunday mechanic and this sort of problem if its electrical will be above your head,check colour of spark plugs and if blackish clean out the air filter,are the brakes binding ??if not and the air filter is clean then run car into local garage,could be anything from low compression caused by worn valve seats to broken piston rings