Tier 2 to ILR with new job

Hi Expertise,

Now I am in Tier 2 General work permit visa since Nov 2013 and it is extended on 2016 and will expire on Oct 2019. At the moment I am in a salary limit of £27500/annum. I completed 5 years of employment under tier 2 to eligible for ILR but my organisation can not afford to pay for £36,000/annum. So I can apply and get another job more than ILR salary criteria with sponsorship. To apply for ILR after changing to new job, how many months payslips need to be submitted? Will they questioned if my salary increases suddenly in my new job? What are all the things I have to make sure before applying ILR? Can you please advise?