Wow, that's a load of trouble isn't it?
Voltage may be a common factor so you may check your battery voltage, it should be around 13.5 volts. You might clean the battery connections too.
You should have around 14 volts with the engine running.
Harboir Freight has an inexpensive digital volt-ohm meter on sale...I paid $2.99 for one....pretty accurate too.
Has the transmission fluid & filter been changed?
The pressure sensor is on the gas tank I think...you might be sure the gas cap is tight.