chevykid53

So i just picked up a 91 chevy 1500 about a couple of weeks ago and ive been having some issues with it. First one is that the tranny wont shift into overdrive. I tried adding fluid and since it was low and it still wont so if anybody knows anything let me know. I believe that its a 700r4 but im not positive. My other problem is that it only likes to start when it is cold outside. If i bring it into a heated shop and leave it in there for more than an hour it will start but then die in a few seconds. It does have a throttle body spacer in it and the previous owner said that the problem started right after he put it in. Thanks for any help in advance.