I'm no automotive engineer but I can't see how opening up the intake passages would help. You want to be operating it with the intake flow kept minimal. I'd stick to basics. Pump up the tires. Learn to coast. Accelerate moderately in lower gears and learn when to lift-off to get into the next gear sooner. Try and keep it in top gear and once in top gear, accelerate slowly or read the road and use downhills for that. Go over hills like you're rising a bicycle - that is let the speed bleed like you only have a lawnmower engine and then recoup it on the other side.
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