Problem with the Craftman 5.5 lawn mower. Please Help?

This mower suddenly decided it didn't want to run strong any longer. I can start it but the only way I can keep it running is to keep pumping the primer thing. Otherwise, if I let it run on it's own it will simply die. Someone said it might be the magnito responding to heat but wouldn't that prevent the mower from running even if I were pumping the primer.

I cleared the gas lines. Checked the float. Cleaned the air filter. checked the spark plug and even cleaned the dried up grass around the business end. What else can I do.

Please help. My lawn looks like a jungle. LOL

Thanks

Max

Max Amillion
March 2008