Not getting to top speed

[amhighfield]

I have 2003 GTX 4 Tec Supercharged. It ran fine before I put it away for the winter. I took it out today for the first time since winter. It started fine but would only reach 40 mph. It usually reaches mid 60’s. Could this be as simple as stale gas?? Hoping. Any help would be greatly appreciated.

 

[pretex]

Change the plugs first. Easiest and cheapest to do. Had the same problem on my Wakepro, wouldn't go over 35.

 

[sktn77a]

What RPMs are you getting?

 

[pretex]

before the plug change, wouldn't go over 5,000 rpm. Changed the plugs, will go to about 8,000 and 61MPH with full tank of gas.