If you have read my post about injectors you already know that I have a loud ticking that gets louder at higher RPMs and only in Drive. I thought it was an injector but now I am wondering if it could be a lifter or pushrod. I would think that a bent pushrod would make a lot more noise. Could it be a lifter?

 

If you think it's an injector, unplug it and run the RPMs up to the point where the noise normally occurs. If the noise is still present, it isn't the injector.

Got a stethoscope?

 

The lifters do not care what gear the engine is in. If the noise changes on that basis, it isn't a lifter.

You have an exhaust leak.

Get a piece of heater hose, take one end and stick it in your ear (I just love telling people to do that!!!) and probe around with the other end to find the noise. Forget the "maybe it's this, maybe it's that thing that 1 car in 10,000,000 has ever had happen", and attack it with logic and reason instead.