I replaced the spark plugs yesterday and some of the power came back but today it all went to crap again . This car sat for about 4 years before we got it last week and I have ran a tank and a half of fuel through it so far . I know it probably had some old fuel in it when we got but I have no idea how much ..... the guy that gave us the car stopped on his way here and filled it up . Am I looking at getting a new set of injectors or should I try and SeaFoam it first ? The engine is 4.6 with 94,000 on the clock and has been serviced religiously by it's previous owner ....... it was his late wife's car and has sat parked since she past away about 4 years ago .