Yz Carb? Problem

[WISEHEAD]

My 02 426 Has Been Stood A Few Weeks While I Make Some Supermoto Wheels Fit. It No Longer Starts As Before, Takes Quite A Few Kicks On Choke & When It Fires Up It Runs Fine On Fast Idle But When You Open The Throttle It Tries To Die As If Its Too Weak. If You Build The Revs Slowly It Does Rev But Gives Flames & Bangs From The Exhaust. Does The Carb Need & Strip & Clean Or Could It Be The Throttle Position Sensor? Any Ideas Welcome, You Guys Must Know The Answer!