here is the thing after a oil change and tires rotated it started flashing the od off light and runs real bad. mecanic had me change the cataletic converter and no change and a mass air sensor and no change. the engin runs fin for a minut after starting then the flashing starts and it goes back to runuing badly pleas help

Iguess it would help if I said it was a 91 sidekick jlx

flashing OD light is related to tranny problems, don't know why it would run bad at the same time though

Does this happen wether you have the OD on or off?

yes it does not mater if the od off is on or off.

Try pulling apart your shifter and disconnecting the switch, see if it still happens.

the thing is it works fine for about 2 min after start up then poop and flashing and run bad

It may be that your computer is waiting for your engine to warm up.   I would disconnect the overdrive switch completely in order to remove it from the equation.  Once that is done you can work on troubleshooting the rest of the electronics.