Case close/conan/detective conan?

I was forgot which episode it is, but there's some episode which is showing conan back to sinichi kudo form, the one is when he accidentally drink paikaru beer (a japanese beer) which is can make the effect of the drug's unstable for some moment, and the other one is when Ai haibara secretly made a drug that can turn back the effect of the drug that sinichi drink (which is made his body become small), then he appeared in the front of Ran in Sinichi Kudo form (adult form) after he drink the drug that Ai gives him

The manga is still ongoing just so you know but Conan has revert back to his Shinichi form several times throughout the series. Its not permanent because it usually last maximum for 48 hours.

This is the list of episode where Shinichi makes an appearance

- Season 2 Episode 48 - 49
- Season 6 Episode 162
- Season 7 Episode 191 - 193
- Season 8 Episode 219
- Season 9 Episode 286 - 288
- Season 12 Episode 400
- Season 14 Episode 472 - 473
- Season 14 Episode 490
- Season 16 Episode 521 - 523

Manga chapter
(Note, you need to read it from the start as I already skipped some the pages to show you Shinichi appearance on this following link)

- Chapter 95
http://www.onemanga.com/Detective_Conan/95/01/
(the case start from Chapter 92)

- Chapter 256
http://www.onemanga.com/Detective_Conan/256/16-17/
(the case start from Chapter 254)

- Chapter 651
http://www.onemanga.com/Detective_Conan/651/08/
(the case start from Chapter 646)

There's also several appearance of Shinichi when Ran is having a flashback

- Chapter 204
http://www.onemanga.com/Detective_Conan/204/18/
(start reading from page 1)

- Chapter 350
http://www.onemanga.com/Detective_Conan/350/06/
(start reading from page 1)

- Chapter 518
http://www.onemanga.com/Detective_Conan/518/18/
(start reading from page 1)

Here's an interesting one (flashback when they are still a kid)

- Chapter 570
http://www.onemanga.com/Detective_Conan/570/08/
(start reading from page 1)

We are not yet sure about that because the series is still not complete even the manga is still going on(i think). But there are instances where conan returns to being shinichi but turns back again to being conan. The first time was when Heiji first appeared from the series and gave conan a certain kind of alcohol. I'm not sure if there was an episode where he turns back again after that but the next one is in episodes 188-193 and the last one was in the latest episodes 521-523.

http://en.wikipedia.org/wiki/List_of_Case_Closed_chapters
here is a link where you can find the list of Detective conan episodes

Episodes 521-523.