Sticky throttle cable, Subaru return spring isn't enough Options

[TonyAKAVW]

Yesterday I got my Subaru engine fired up for the first time (see my progress thread for a video) and I proceeded to hook up the throttle cable to the pedal. I'm using a brand new Terry throttle cable which is connected to the Subaru throttle cable. Both cables have very little friction and are in new condition. However, when I push down the pedal it doesn't come back up fast enough (or somtimes at all).

My first idea was to add more throttle return spring. I added the two springs that were on my 1.7 engine and it helped a little, though not quite enough. My concern is that there might be something going on in the car portion of the tube or at the pedal itself.

When I pushed the throttle cable through the tube in the car initially, there was some resistance and a little rusty powder on the end of the cable. So I'm sure the tube is partially rusted inside, at least at one spot. Will that make a huge difference?

So what I'm looking for is some suggestions on where to look. Does the throttle pedal itself tend to stick or is it the tube? Would it help if I found a piece of teflon sleeve to line the car's metal tube with?

-Tony