I'm expecting around 3-4000 rank in Jee mains .bt I did miserably in other exams.should I go for nits or drop 1 yr for iits ?

It depend on ur choice . well u can take nit and start preparation for iit with ur colleges or u can drop for 1 year if u have confidence that u can select or can do better . but in my opinion u can go through gud nit like warangal , trichy etc.