She is suffering from waswasah and is asking whether the scholars were affected by waswasah too
Question

                My question is about waswasa. In my life, when I tried my best to practice Islam at that time I felt great waswasa. Still now I feel waswasa. Time by time it change its form. My question: does every believer feel waswasa? Famous scholars like ibn Taymiyyah and Imam Ahmad, did they feel waswasa? If they felt how they work a lot for Islam?
Praise be to Allah.Waswasah (whispers from the Shaytan) is one of the evil methods of the Shaytan, the whisperer (devil who whispers evil in the hearts of men) who withdraws (from his whispering in ones heart after one remembers Allah) (cf an-Nas 114:4). This is always his way: he whispers into people’s hearts, and strives hard to cause harm to the believer’s religious and worldly interests. This is something that happens to all people, despite the differences in the extent to which the Shaytan is able to reach each one with these whispers,  whether small or great, whether they strive to ward off the enemy until they defeat him and overpower him, or they surrender to him and yield to him. 
Muslim narrated in his Saheeh (2814) that ‘Abdullah ibn Mas‘ood (may Allah be pleased with him) said: The Messenger of Allah (blessings and peace of Allah be upon him) said: “There is no one among you but Allah has appointed a companion for him from among the jinn.” They said: Even you, O Messenger of Allah? He said: “Even me, but Allah helped me with him and he became Muslim, so he only tells me to do good.” 
An-Nawawi (may Allah have mercy on him) said: 
With regard to the phrase translated here as “he became Muslim (aslama)”, there are two well-known narrations of this phrase. According to one narration, the word is to be read as aslamu, which means: “I am safe from his evil and temptation”; according to the other narration, the word is to be read as aslama, which means “he became Muslim”; what is meant is that the jinn-companion became Muslim and became a believer, “who only tells me to do good.” The scholars differed as to which of the two versions is more correct. Al-Khattabi said: The correct version is “aslamu” whereas al-Qadi ‘Iyad thought that “aslama” was more correct, because the Prophet (blessings and peace of Allah be upon him) said: “[he] only tells me to do good.” They also differed concerning the meaning of the word “aslama”. It was said that what was meant by the word aslama, translated here as “became Muslim” is that he surrendered and yielded. In a report narrated in books other than Saheeh Muslim, the wording appears as fa istaslama (he surrendered). And it was said that what is meant is that he became a Muslim and a believer, which is the apparent meaning.
 Al-Qadi said: It should be noted that the ummah is unanimously agreed that the Prophet (blessings and peace of Allah be upon him) was infallible and protected from the Shaytan in his deeds, thoughts and speech. 
This hadith indicates that the warning refers to the temptation and whispers of the qareen (jinn-companion); the Prophet (blessings and peace of Allah be upon him) told us that the qareen is with us so that we may protect ourselves from him as much as possible. End quote from Sharh Muslim (17/292) 
The time when the Shaytan is most eager to whisper to a person and gain control over him is when he wants to focus on his prayer and worship. Hence when it was said to Ibn ‘Abbas that the Jews claimed that they did not experience any waswasah in their prayers, he said: What would the Shaytan do with a ruined heart?! Al-Wabil as-Sayyib by Ibn al-Qayyim (40) 
What you should do is not worry about whether the whispers of the Shaytan came to So and so, or what So and so did. Rather, what you should do is strive to rid yourself of the tricks and whispers of the Shaytan and his attempts to gain power over you. 
For information on ways of dealing with waswas, please see the answers to questions no.  62839 and  39684
And Allah knows best.