96 grand cherokee

someone please help,i have a 96 jeep grand cherokee and i keep getting a po351 error code after i have replced distributer, wires ,plugs and tps but nothing helps.i tested the coil and got pleanty of spark also it keeps blowing the muffler ,its done it three times so far ,i dont know if there related but i'm going nuts trying to figuer it out.:runaround:

did you get the problem resolve and how