Hello all! I am new to this forum, so here goes. I have a 2005 F-150 with the 4.6L 4x4. I have 98K on it. I just recently replaced #7 spark plug and coil due to a misfire. Dont think that has anything to do with this problem, but shoertly after I staretd getting a shudder/vibration when taking off in reverse. It only last for 1-3 seconds with gas peddle pushed, if i let off and push again, same result. To me, (not a ASE cert. mech. by any stretch of the imag.) it doesn't feel/sound like gears aren't matching up. Any suggestions would be appreciated.