Coasting @20mph and going 60mph every 20 sec's there's a drag

What is your question?

I've had this car for 22 yrs and 10 yrs ago my tranny solonoid went out so the un-plugged it and since then I get a check engine lt and a code 26 27 28 .,ashop told me it was tires another said i needed a new computer @$500