Qualcast 35s running Problem

We have a qualcast 35s that does run but doesn't like to run any faster than tickover. If you do increase the speed it has sparks coming out of the exhaust. Anyone have any idea what could be wrong? We have cleaned the carb but don't know what to try next. Thanks in advance for any help
--
mandyc

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.