im hving a problem with my t-bird sc. it idles and revs good but if i hold the gas down to keep the same rpms like 2,000 it drops around 1500 then the rpm will go back up. when the rpm drop i get a pop and crackle sound from the exhaust. can anyone help me out or has anyone had this problem before? ive already changed the plugs and wires,fuel filter,maf sensor,and hb and the crank sensor and has new cam sensor. i bought car with a bad hb and went with the bhj.