i would do 2 things first, i would check my fuel pressures, on a 1983 240 turbo there is a vacuum hose setup going to the warm up regulator, one line has a check valve and the other one splits off and connects without a valve. i would replace the check valve and the vacuum hoses, make sure you put them back exactly the same way and the white half of the check valve facing the vaccum source, which is a wax switch on the cylinder head right above the regulator.

the other likely problem is your injector seals are leaking, you should remove and clean the injectors and replace both seals. i think part # 463113, and 463115, but im not sure about those numbers.