I have a 1998 Tahoe with a 5.7. over the last 6 months or so it has become increasingly harder to start. had to have a new flywheel installed about 3 months ago and put on a new starter about a month ago. for the last month it has not been starting. It cranks like it is out of time or binding maybe. so far i have advanced the distributor by 2 teeth and the went 2 teeth retard with no change in cranking. every once in a while but not very often it will crank like it should but then go back to the cranking like it is out of time again. this past week end I checked again to verify that it has spark whick it does, it has 61psi fuel presure with key on not cranking and 50psi when cranking. this weekend i also tried a different distributor with no change so when i put my original distributor back in and set it according to the chevy service manual it cranked less than one full turn and started. i let the motor run for approx 10 min shut it off and now it is like it is out of time again. any help would be gratly appreciated thanks in advance.