We used to call that approach being a "wheelbarrow mechanic". Roll a wheelbarrow full of new parts up to the job and start swapping parts until the performance improves or the problem goes away. Leave all the new parts in place and write up a huge bill. "Well, that part was bad anyway even if it didn't solve the problem!" Mechanics and/or shops that tried that tactic usually didn't stay in business long, as it was pretty common to create more new problems than they fixed. Work on one thing at a time until you're sure it's right, then move on to something else if necessary.
Jerry
