Small Engines (Lawn Mowers, etc.): rideon lawn mower, engine model type, carburetor

Question
Hi, my mtd ride on lawn mower will  start, rev high then drop ,rev high again then drop, this is continuous. is this just a need of oil? what is rhe possible problem?

Answer
99% of engine surging/hunting is caused by a dirty carburetor.  How old is the mower?  When was the last major tune-up including an oil change and carburetor cleaning/overhaul?

What engie is on the mower?  What is the engine model, type and code/serial number?

My bet is the carb needs to be cleaned.  Do you have an air compressor to blow out all the carb orfices/holes for cleaning the carb?

Let me know.
Eric