The valves require adjusting on cars without hydraulic lash adjusters because of not just cam/rocker wear - the primary cause is actually valve seat wear. The valves themselves wear as do their seats, which is why they usually wind up "Tight" on the rockers (open slightly when they should be closed).

If you had valves not closing, you were losing a fair bit of power, as the combustion was leaking out. If it was leaking into the exhaust it's power loss, but if your compression or combustion leaked back into the intake manifold, you wound up with higher manifold pressures as well, which really throws DJet for a confusing loop. Now that your valves are set properly, check your timing, dial it in right if needed, and THEN adjust your CO mixture at the tailpipe with an old-school sniffer or a wideband O2 sensor (there are DIYs on how to make your own sniffer with one, but it probably costs more than finding an old mechanic to take 30 mins to dial you in).

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Current:
2021 Charger Scat Pack Widebody "Sinabee"
2018 Durango R/T

Previous:
1972 280SE 4.5
2014 Jeep Grand Cherokee Limited "Hefe", 1992 Jeep Cherokee Laredo "Jeepy", 2006 Charger R/T "Hemi"
1999 Chrysler 300M - RIP @ 221k