Constant Ticking Valve M103 motor

[ZenkiGuy]

Before I begin, I've seen a few threads with similar issues but I haven't really got my issue answered.

1988 Mercedes 300CE with 172,xxx miles.
- Oil changed every 3,000 miles with Rotella 15w-40.

When I first bought the car, it had no valve tick at all (162,xxx miles). I moved across country and drove her 2,600 miles with no issues. It always had a rear tick sound for a couple seconds as soon as it cold started after sitting for a good 12 hours.

Last month, I started trucking and left the car sitting for 4 weeks. I came home, put some fresh gas in it and it cranked up immediately but had some hesitation so I revved it to keep it running. I accidentally revved it to 3,000 rpm as soon as I cranked it and it started ticking constantly. It's not a loud tick and it actually is a very quiet tick. I know these cars have hydraulic lifters so they can't be adjusted. I've also read that replacing 1 quart of oil with auto trans fluid for a 500 mile cycle can "unstick" any "stuck" lifters. Revving it that high was a mistake I think caused the issue. Hopefully it's nothing major or I'd probably have to sell the car due to going into college for a 2nd time and can't have huge car expenses in the near future.

- Any advice on fixing the issue or things I should look at would be great. I've read on Pelican Part forum that a nice "highway blast" can fix the issue as well. Other than the tick sound, the car runs fantastic!

Any other info. needed I can give.

Thanks,
Jonathan