Time for spark plug change

[Big_Pezzy]

I've been meaning to replace my plugs for the last couple of months but kept putting it off. Not that the engine has been misbehaving. Just because I have had my vehicle for 35k miles and have never replaced them. The other day, I noticed my RPMs drop drastically (less than 500) once I put it into park, it has a second of hesitation and then goes up to 500. My co worker said it is the spark plugs or possibly the wires. My question is, which wires and plugs do you recommend? I stopped at Autozone today and the guy suggested Autolite XP Iridium and the Uralast Gold wires since they have a lifetime warranty. Total would be about $90. I have been saving up for a CAI and exhaust, was going to do them at the same time, but now i have to do this. I only mention this part because I have read that if my vehicle is stock, I should stick to OE replacement parts. I have looked into the products available from performancedistributors.com and was going to buy the ignition coil and wires from them after my intake and exhaust. Do you think I should go with the autozone products and replace right away? Or can i wait 2 weeks till my next check for the upgraded parts

 

[1998Exp]

"Best plugs and wires" has been the topic of many discussions on this site. It's more of a religion than science, and I have nothing to add to that debate. HOWEVER, if your coworker is not an auto mechanic experienced with this generation of Explorers, I would take his diagnosis with a large grain of salt. If I may risk a guess (which you are welcome to ignore, of course), unstable idle is typically caused by a malfunctioning IAC (idle control valve). And if you are lucky enough to have the check engine light illuminate, you should have the trouble codes read - there may be a good clue there. Best of luck!
By the way, it helps immensely to provide your Explorer's engine type (there are three different ones) and configuration (transmission type, drive type). You will save yourself a lot of silly advice if we know those things. The best place to provide them is in the 'Vehicle Specs' field of your profile.

I've been meaning to replace my plugs for the last couple of months but kept putting it off. Not that the engine has been misbehaving. Just because I have had my vehicle for 35k miles and have never replaced them. The other day, I noticed my RPMs drop drastically (less than 500) once I put it into park, it has a second of hesitation and then goes up to 500. My co worker said it is the spark plugs or possibly the wires. My question is, which wires and plugs do you recommend? I stopped at Autozone today and the guy suggested Autolite XP Iridium and the Uralast Gold wires since they have a lifetime warranty. Total would be about $90. I have been saving up for a CAI and exhaust, was going to do them at the same time, but now i have to do this. I only mention this part because I have read that if my vehicle is stock, I should stick to OE replacement parts. I have looked into the products available from performancedistributors.com and was going to buy the ignition coil and wires from them after my intake and exhaust. Do you think I should go with the autozone products and replace right away? Or can i wait 2 weeks till my next check for the upgraded parts

 

[Big_Pezzy]

Honestly, I was never able to figure out how to change my vehicle specs. But it is an '01 sport with the 4.0 SOHC, 5 speed (not sure on the transmission number), 2WD, 3.73 LSD if that helps. I came here because I did take it with a grain of salt. He is not an expert of 2 gen explorers but, he is pretty knowledgeable of cars. I work at a car audio place, and believe me, people come to us for more than speakers. This guy, 28, has been working there for about 10 years, is an expert on car electrical systems, and very knowledgeable of engines. He's had several cars, all kinds of makes and models, and had worked on them himself. I only ask if anyone has any other possible diagnosis. No check engine light so far. This is why I am pretty unsure of what it could be

 

[swshawaii]

1998Exp offers excellent advice and the IAC is the first and easiest place to check for idle surging. Seeing you have a 2001 Sport, also check the trouble prone PCV elbow that does NOT always throw a CEL or the p0171/174 trouble codes. Should you replace plugs, use the OEM Motorcraft SP500, Autolite APP103, or XP103 designed and proven to work very well for this engine.

Cleaning the IAC Motor
http://www.mysporttrac.com/mysporttrac/projects/CleaningIAC/CLEANING_IAC_MOTOR.htm

Throttle Body Cleaning
http://www.mysporttrac.com/MySportTrac/projects/ThrottleBodyCleaning/Throttle_Cleaning.htm

P0171 & P0174 4.0L SOHC's Sport/Sport Trac
http://www.explorerforum.com/forums/showthread.php?t=314670

Sticky: Add Complete Vehicle Specs To Your Profile (Thread Display Options)
http://www.explorerforum.com/forums/showthread.php?t=375816

 

[Flash]

All the good answers were already taken so I've only got "check for vacuum leaks" to offer.
It's probably the IAC but it's a good idea to clean the PCV and throttle body too as previously mentioned.

I like NGK Iridiums, they're the recommended plug here.
I don't know if I can even get Autolites here.

That idle condition you described is not symptomatic of crook plugs and leads.
Bad plugs and leads will break down under heavy load and often return to normal at idle.