Need help going back stock

[imca9j]

Im looking at 1987 t type turbo. it is methanol injected when the boost goes to 20. has bigger turbo and computer is programmed to make the boost. i want to take off the methanol and reprogram computer. is this possible and still leave the larger turbo. he said it needs a crank sensor runs great but sometimes dies after its been driven a while. he said he waits about 5 minuets and it restarts the fuel gage does not work he thinks it could be related to the crank sensor i dont know any help would be great