Somebody claimed so once dont remember the details but I think it just created more air leaks for him. The problem is the spacer is supposed to help atomize the fuel spray better by creating turbulance. But since the actual injectors are outward on the manifold and not on the TB the turbulent air would smooth out when it reaches the injectors and have no effect on breaking up the fuel particles further.
---------- Post added at 12:38 PM ---------- Previous post was at 12:27 PM ----------
If your engine is running good with good acceleration I would suspect that you have no restriction in your exhaust and if you have no computer failures I would leave it alone for now.
If there is a malfunction somewhere it will rear itself eventually.
How about getting your hands on a cheap tach the clips over a ignition plug cable.
You might be able to get a local parts store that could scan you truck so you can compare the tach readings. ANd check your code history while your at it.
Your vehicle one reads off the igntion coil so if the readings don't jive then your dash one has got to be in error as long as you can verify 12 volt supply to the panel.