I just had my transmission rebuilt in my 1998 Ford Winstar the overdrive light is blinking and it sticks a little in drive the scanner is reaing a transmission sensor and upstream exhaust sensor will this cause the problem it also is sometime hard to start and has a gas smell is racing and sometimes wants to stall out.

Transmission sensors a notorious for causing shifting problems in older vehicles. The problem is usually getting to them. Upstream exhaust sensor is undoubtedly the oxygen sensor.