I have a 98 sierra with the 350 and i bought it a few months back and have steadily been replacing parts trying to get it back to a good running and driving condition , as of the past few weeks ive been battling a problem with a p0340 and p0102 code , ive replaced the plugs , wires , maf sensor , cam position sensor , and flushed it , cleaned everything up , but it will not budge . When i put it in drive or reverse at first start it gets real excited and goes fast by itself , changed the throttle position sensor it isnt as bad but still there . It doesnt give me too much of a problem if im in 3 at normal hwy speeds 45-55 , but once i hit 60 it starts to act like somethings binding up or it doesnt wanna go any faster . In D it shifts too much and shakes like hell at about 45 . Doesnt really misfire a lot since i replaced the plug wires but now sometimes itll dead miss one time randomly and then catch back on all 8 again like nothing happened . Also in some cases if i let off the gas too fast itll jerk real hard . I cant lay a finger on it next step to me is to replace the whole distributor and hope for the best . Any helpful insight is appreciated , thank you