1994 Chrysler LHS Check Engine Light

I recently purchased a 1994 Chrysler LHS w/125,000 miles on it. After the gas got down low, I filled it with gas. The next time I started the car, the Check Engine Light came on and stayed as I drove to the store. When I came out, I let the engine idle for a few minutes thinking that might help and the light did not come back on. This happened a couple of times. Since then, the CEL has stayed on. After reading your archives, I am hoping this might be from the gas cap not being on tight enough. Since I just bought the car, I really don't have much money to put into it right now. Our local repair shop said they would charge $100 just to find the codes. Do you know if Auto Zone or any other place can put the computer on it for free? I also seem to have a number of oil leaks, including some on the chrank case cover. There is also a tie-rod that needs replacing, can you tell me the cheapest way to get it repaired? Is it difficult or time consuming? Thank you.