p0330 random misfire, followed by p0334 CamPosSensor code

chevy 07 3500 express van w 8 cyl 6.0 L vortex. 56K long distance miles on it. started showing P0300 random cylinder misfires w/ occasional steady MIL in June 2021. no loss of power, drop in gas mileage, starting problems, it runs fine. Rxs: replaced points plugs wires, tune up. cleaned MAF, cleaned/ checked engine grounds , did professional injector clean. . shop#1 finally replaced crankshaft position sensor, MIL light went off for 2 months. it came back , always coming on at mph over 50 on an uphill grade but never at city speeds 3- 30 mph . (2yrs ago, a downstream B1S2 was replaced as it was showing its code. ) shop #2 rx : "CkPosS was not an OEM, so replaced again and re learned. rx relearn CkPS (2x 100$ each. MIL went out for a month, came back on , this time alternating flash, then steady then off. chevy dealer shop #3 reflashed ecu , no joy. then replaced cam position sensor. $500, no joy. after CamPS replacement, MIL p0330 always comes on now, even on startup at o mph and code 0334 comes on occasionally.. MIL is steady at all times now even w cold engine then goes to flashing when when going UP a hill at more than 50 mph while pressing throttle pedal to maintain speed up hill . MIL disappears temporarily when foot comes off throttle pedal at top of hill, as I 'm coasting down hill. MIL always comes back on flash or steady going up hills at 60 + . after #3 chevy dealer repair, van is now throwing p0300 code and occasional P 0334 for cam position sensor "not aligning w CkCPos sensor within 5 sec. "

ideas: some problem w throttle linkage ? bad ECU ?
I have thrown $1400 of parts and diagnostics from 3 different shops at this problem.(including #3 the dealer. ) no one is willing to let me drive in w engine hot and flashing the DTC codes to , pull flash and live data themselves on the cylinders. no-one tried a cylinder wire swap to the plugs or pulled gulping patterns. , no one wanted to look at my actron live data .
all suggestions welcome. . . . I'm an EMT and a scout leader. I haven't been able to drive my van log distances at more than 50 mph nowadays since jun 2021, because of the codes .

Mitch,
Sorry to see you paid so much money for no fix. This is what happens when the parts cannon has no fire discipline.
To make sure, you cite P0330 and P0334. Those are knock sensor codes. A lean misfire can cause these codes.
I'm going to reread your post again.

hey ScannerJohn --
some misinformation. the chevy dealer 'tech guy' told me 334 which I w rote down. my own scanner an ACTRON is showing the code as p0336 not 334. chevy dealer does not write down the codes on my recent $500 bill for the cam sensor-- just told me 'I need a new timing chain. .' . '

mitch m -- (my 3500 express is in your shop now ! ( the actron w its 5 stored readings of live data is on the front floor. )

If it is a timing chain engine I would start there.

That does make a difference... You mentioned the crank sensor was replaced previously and all was well for 3 months. This suggest to me a possible wiring problem. The P0336 sets when the PCM does not receive a crank signal within a few seconds. Locate the sensor, possibly near the starter, check the connector and wiring. Insure the connector pins are secure in the connector and do not back out when you pull on the wires. My thought is the green sensor wire may be loose and making intermittent contact.

I don't know what your mechanical abilities are or what testing equipment you have, so I'm giving you things to do that don't require much. I would not go out and have the timing chain replaced based on the info you have. I would do more testing before doing the work or paying someone to do it. Heat, vibration, contact points and moisture cause most wiring problems. If you have an oil leak on the wiring, clean and inspect it as I mentioned above.