engin fault codes and sensors

[juliet 0]

Hello, i have 4 fault codes, on my very early vr6, 65535 which im sure is the fact there is a dastec chip bolted onto the top of my exsisting ecu, this currently has the standard map in it, it had to be re programed so they stuck statndard map in until i can rolling road it if ever. The second is 515 which im certain is the hall sender in my dizz, which i would like to know where i can get one, 3rd is 533 and 4th 513 one of these come back as G28 sensor, where is the G28 sensor ( engine speed ) on my 92 - 93 vr. This car a pain in neck and like iv always said pulls like shit of a hot shovel in the morning when cold, but warms up and hesitates.

am i right in saying that it is a possibility that the engine speed sensor will always throw up this code because when not running its not working, could then this be also true of the hall sensor in my distributor. leaving the ideling type fault as something i just dont know about. the car admitadly has recently been ideling at a higher rate than normal. about 12 to 13 hundred RPM. normally it would sit down under 1000 Rpm. If there is something wrong could it be the ISV. Dont think this is MAF or Lambda related, recently drove to exeter from cumbria, 70 to 80 all the way 32 mpg, so dont think its these to sensors.

my only other thought on the matter is the reason or getting the dastec cip re programmedis because it nroke. it was spiked by something, welder, electrical short and the car wouldnt run, without disconecting the maf. once this was reprogramed and returned it runs or should i say ticks over, no splutters. Is it possible that what ever spiked the bolt on chip also has damaged the cars original ecu.

sorry for the long winded ratnt but iv never got to the bottom this cars hesitation problems. Any help would be appreciated

Thanks

Homer