Constant malware infection

Hello everybody!
I have a wordpress site BUT I have a problem
Everytime I install a new plugin (or remove one) after one day or so, clicking ANY link, a new popup window open up with annoying ads (propeller ads etc)
To fix this I use gotmls, which cleans the malicious files
In fact I find that some js files (and some php ones) are injected with encoded malicious code (eg \\x64 \\e43 etc etc). Last time even cron was infected
I have tried various plugins to protect my site (ithemes etc) with NO luck whatsoever
All admins etc will change our passwords but what next?
Any ideas on how to scan and effectively protect my site?

PS My problem is like the one described in this old post

• This topic was modified 7 years, 4 months ago by braveheart1980.
• This topic was modified 7 years, 4 months ago by braveheart1980.