60hp mercury vigfoot 4 stroke

[ronnie0328]

I have an 05 60 hp 4 stroke merury bigfoot motor that is on an 18 ft suntracker pontoon. Purchased the boat a few months back. It had been sitting since purchased brand new in 05 and had only ran for about 20 mins on the water. We changed out the oil and lower unit oil before putting it on the water and it did great. Now for the problem, when i go to accelerate the alarm on the RPM sounds and it stalls until you get the RPM back below 3000. It would originally go to 4500 RPM and run about 16 mph. Any ideas on what would make it redline out? Thank you for any help it is appreciated.