Throttle body cleaning?

welcome!
it won't hurt, but you're right, it's a very different design and that includes misdesign.
the gen 3 engine (includes all prius v) has a poor egr setup which clogs the egr valve, cooler and intake manifold ports, as well as dumping the remaining shmutz into the throttle body.
take a look at this video. you might consider attempting it soon, and changing the oil and filter every 5k, if you aren't already.

watch

and this guy is funny:

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The throttle body wasn't very hard to get too. I was surprised how clean it was at 140,000 miles. Perhaps someone cleaned it at some point previously. In anycase, my only advice will be if you remove the big throttle body hose - learn how the clamp works such as it clips back fully open. Then you can work the big hose on to the throttle body nice and perfectly all around before releasing the clamp. Failure to have that hose on fully will result in your engine throwing a crap load of codes (technical term) and shutting down (ask me how i know). You would not need to remove the coolant lines from the throttle body to clean it.

I recommend removing the airbox and large air hose to the throttle body. I remove the airbox to ensure the large air hose is clamped on perfectly and i can see all around it.... your call. I cleaned with carb cleaner and a towel to get all the build up off. Not sure how effective it would be without manually wiping it down.

 

This is for regular 3rd gen Prius, but I'd think it'd be applicable for Prius v throttle body cleaning:

^ He recommends to not spray carb cleaning directly, instead spray it on a cloth or swab, just wipe.

If you really want to do a thorough job, and clean the "sump" at the bottom of the intake manifold below, I'd recommend to disconnect the throttle body's hold-down bolts/nuts (2 of each), the electrical connector, and lift the throttle body right off. You definitely don't want/need to disconnect the coolant hoses; they have enough slack that it's unnecessary.

The attached shows torque values for the throttle body hold-down nuts/bolts, both are 7 lb/ft IIRC. A 3/8" or 1/4" drive torque wrench would be appropriate for such a low value.

If you're ambittious, go further, remove and clean the intake manifold? Pay special attention to the small EGR passages, one per port.

Also timely to clean the EGR components, see first two links in my signature. (On a phone, turn it landscape to see signature.)

 

So I think I messed up. I removed and cleaned my throttle body on my 2010 Prius, and now I'm having very weak acceleration and rough idle. I messed up by manually opening the valve to clean, which I now know is not recommended.

Is there any way I can correct this?

 

I’ve never heard that. It seems mandatory to push the plate open to clean properly.

Did you take the throttle body right out, pull off the coolant hoses? There is enough slack on those hoses that you don’t need to do that. If you did, there might be air pockets in the coolant system, though not sure if that could be a factor.

You’ve double checked the electrical connector?

The hold-down nuts and bolts (2 of each) torqued to 7 ft/lb, gasket in place? The plastic snorkel above not misrotated? All its clamps secure?

The air cleaner box and snorkel all back together properly, MAF sensor electrical connector secure? Ditto for top PCV hose: it’s pushed back on, secure?

 

I double checked everything you mentioned and nothing was amiss. As a last measure, I disconnected the 12 volt battery in hopes this would recalibrate the idle. Lo and behold, this seems to have worked. I drove the car for about 40 mi and the was riding like new!

 

Mendel, I just realized that I did not torque the hold down nuts at 7 lb. I probably need to go back and do that properly. Doh!

 

It is necessary to handle the throttle valve mechanism with care.
Plastic gears have their own strength limit.
If you break a couple of teeth on the drive during strong mechanical turning of the closed valve, you will have to look for a new throttle valve mechanism.