Hi I cannot find the Auto Complete plugin for Salesforce IDE which I have installed in Eclipse. Version: Kepler Service Release 2
It looks like it might be coming soon according to the idea here.
The developer console now has autocompletion for Apex code, in addition to its long tradition of autocomplete for Visualforce. Can I get a huzzah from the crowd?
We will add this to the IDE plugin as part of our refactoring to utilize the Tooling API in the coming year.
It looks like there is a visualforce plug in here, but haven't tried it out.
Something else I haven't tried but it looks like auto-complete is part of the beta install, Changes in Force.com IDE Beta Version 184.108.40.20650511 and Downloading the Beta Version of the Force.com IDE.
It's been broken for quite a while now (link)
Personally, I use Mavensmate with Sublime Text 3 for day to day development.