It might be just because I run a higher end servo (actually middle grade $70) that moves very easy with minimal spring. I have a very light spring on all three of my rigs (slayer/savage/aftershock) and when I shut off the power, it easily moves back. The jato on the other hand... I never put one on it. It runs mostly on faith anyway.
The throttle linkage is covered up a bit from the stock roll bar, but you can see enough to see what I'm talking about:
Nothing special. Just setup the way my savage and aftershock are. The spring on the rod allows the servo to move when applying brake, but also gently holds the throttle closed. The spring you see connected to the pivot is the TRS. It's a fairly soft spring that also applies a bit of pressure when at idle, but is enough to move the throttle servo back home when power is disconnected.
It's a piece of threaded end piano wire you can get at your LHS and little du-bro captured ball end on the throttle pivot. I hate using z-bends... they get sloppy in a short time. I don't care for slop in my linkage. You'll notice the rod on the left of the slider on the servo is bent in a bit. This is to keep the body from rubbing on it when I hit stuff. The slide arcs in that direction anyway as the servo turns and slides fine. I proffer the wider slides as they move better on the wire and don't bind like a more narrow slide does after a while.
I use bearings in the throttle pivot vs the nylon bushings that are supplied. Moves nice and smooth and also, doesn't wear and cause slop.
No bind, no slop.
Also, the servos I use for t/b duties are hitec 985MG's. Strong, fast, metal geared and sealed with o-rings (especially on the output shaft). The sealed part is very key in my book since t/b servos almost always stand upright, they are the ones most susceptible to water damage. And 99.9% of the time, if a t/b servo gets water damage, it goes WOT on you and almost never goes to full brakes. Actually... for me, 100% of the time WOT... so, now I spend a bit more and get a good servo that lasts years. The one on my savage is probably 4 years old. It's been in 3 vehicles... maybe 4. When that happens, the TRS and FS are a mute point as neither do you any good. The only thing you can hope for is that you can steer it into something soft as it's screaming out of control. Also... in my experience, there's never a pile of hay for you to run into... I usually hit trees or a concrete wall... a curb... myself... I digress.