2 Questions Please Help

[GELLIS2586]

1. My car grinds third gear whenever I am in the upper rpm range (5,000-redline) I was wondering is there any cheap way to fix this or is it something expensive like a synchro going out.

2. My ecu keeps throwing codes for no reason at all first it was the egr, then throttle position sensor, and now it says that the crankshaft balance sensor (or something like that) is screwed up. Why would my ecu keep throwing codes if there isn't any problem. Could I get this fixed by getting a JWt ecu.

[quiksilvia]

most likely that a new ecu will help, maybe get a used one and see for sure, prolly the syncros, try switching to redline mt 90 or mtl if necessary for the grinding

[GELLIS2586]

Would royal purple be a good oil cause im getting an oil change this weekend and thats the motor oil i use so would the transmission oil be as good as redline or should i buy some redline.

[quiksilvia]

either or