i just bought a car that has been sitting for 3 yrs with approx. 10 gals of gas in it. i drained as much of the gas out as i could,replaced the fuel pump and started it up and it barely runs. it has very little acceleration and sputters and misses alot. it's an 89 pontiac firebird 2.8 fuel injection.i suspect clogged injectors is there any way of cleaning them myself and what else can i do to get it running good