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2003 Forester 2.5X 5MT & 2008 Impreza WRX 5MT & 2009 Impreza 2.5i 5MT
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293 Posts
Discussion Starter · #1 ·
I have a 2003 Forester 2.5X with 5-speed manual. It has 142,000 miles on it. I just bought it recently and I have been driving it daily. So as the title says the throttle response is sluggish.

I have cleaned the throttle body and IAC valve with CRC throttle body cleaner. that seemed to help. I then did the Subaru idle fix / idle relearn. this seems to have really helped with the stuttering I was getting when accelerating in first gear from a dead stop.

My next step is to replace the spark plug wires and spark plugs. Here's where I'm confused and need recommendations from you experts. I plan on installing NGK iridium spark plugs, but I'm confused on which part number for the plugs. Napa Auto shows the part number as NGK 3764 , but Amazon shows the part number as NGK 5464. I realize these are two different plugs and I don't want to damage my engine by installing the wrong plugs, yet I want the best possible performance I can get from my engine. In short what iridium spark plugs are you guys installing on your 2003 foresters with the 2.5 sohc engine??
 

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Registered
2003 Forester 2.5X 5MT & 2008 Impreza WRX 5MT & 2009 Impreza 2.5i 5MT
Joined
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293 Posts
Discussion Starter · #5 ·
After doing some research the 2003 Forester Owner's Manual recommends NGK (2756) BKR6E-11 and NGK (6953) BKR5E-11 spark plugs. So I may end up installing one of these.
 

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Registered
2003 Forester 2.5X 5MT & 2008 Impreza WRX 5MT & 2009 Impreza 2.5i 5MT
Joined
·
293 Posts
Discussion Starter · #7 ·
I finished changing the spark plugs. I went with the NGK BKR5E-11 (6953) plugs.

Funny thing is it already had the Iridium plugs in it. I attached a pic of the plugs I pulled out of the motor.
 

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