I have solara 2004 v6 it starts vibrating b/w 30 to 55mph and than go away if i accelerate more unto 70 or 80mph.

Try having the front wheels balanced and tracked .

change fuel filter

You have problems with the driveline angles.There are TSB that the dealer has to go through.This is common for Fords

Yes this engine is interferance, if the timing belt breaks or jumps the piston to valve damage will occur, good day/.

Behind the glove box or under the front cawl beneath your window wipers check your book on the car go to index and look up cabin air filter.

DON'T NEED A DIAGRAM.. JUST GO AROUND BASE OF PLENUM AND REMOVE SCREWS.. MAKE SURE TO HAVE A NEW PLENUM GASKET RO REPLACE FOR OLD ONE

The sending unit in the tank.

If you need further help, reach me via phone at https://www.6ya.com/expert/jason_e95d2f9c1ac9610d

U can't test the new OBD2 system (1996 up) that way, u need at a very min a code reader, better choice is a full function scanner.

Check to see if the radiator fan relay has gone bad and needs to be replaced. Once you located the relay, (in the fuse box under the hood) Try swapping it out with another relay and see if the fans stop, if the fans stop working with the swapped relay, replace the relay. It's know for the relays when they go bad to stick and will have a close loop. Good luck and hope this helps. Keep me posted, be glad to help you get your car running 100% again soon.

Have a mechanic read the trouble code(s) from the computer. They should point to problem(s) that the computer senses as fault(s).