If you are able to determine the O-ring is leaking, I would just ask a mechanic for an estimate.
I cannot say whether your '94 is the same as our '93, but it is not that bad to do it yourself. I made it harder than it needs to be.
Get the following before you start:
New o-ring, throttle body gasket, throttle body cleaner, and throttle body coolant lines.
I spent too much time trying to remove the old coolant lines before I just cut them off. The dealer was not open, and Oreillys did not have the exact replacement for the formed hose, but they were able to find a similar hose that I cut down to size.
When I went to pull the shaft out, it was really stuck. I spent too much time pulling on it before I got aggressive with a pair of vise grips and more muscle. I think it was just "varnished" in place.