My van's front catalytic converter heats up and misfires after 30 minutes. on 2001 Toyota Sienna

My front catalytic converter turns red hot and cylinders 2, 4, & 6 begin to misfire. The engine code reads misfire in the three cylinders. There is very little exhaust when the vehicle begins acting up. I have removed the front catalytic converter but the three cylinders continue to misfire (no where near as bad as it was before cat removal) and the engine codes still reads misfire in cylinders 2, 4, & 6. The spark plugs have been replaced. Any suggestions?

Asked by for the 2001 Toyota Sienna
Sounds like excessive fuel is being burned in the cat. Possible injector/pressure regulator problem. Black smoke from exhaust?
No black smoke. So, its now code 1354 which is the vvt and ocv? Is that expensive to repair?
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happy bayner road.(banier road.)Essex,baltimore,marylande, happy America.mrs.maggie mae Whittington.montgomery & children-miss.charlese ann,miss.lakisha ivenola,miss.anita ann,mr.kerry lee,mr.michael Lloyd Montgomery jrs,and husband-mr.michael Lloyd Montgomery sr.(duvall.)218843488/02/14/1974/(13.).3488.
So now its code 1354 which is the vvt and ocb. Is that expensive to repair?