Fuel Injection problems of the 1997 GMC C1500

Engine started misfiring, shaking and burning gas like a gas guzzler, took it to dealer and said that two injectors were damaged, replaced one and repaired the other. At idle (750 rpm)speed engine is intermittent . As for the steering, while driving at cruising 45-65 mph it was impossible to control vehicle, steering felt like a feather in the air, uncontrollable. Unit was taken to dealer in three different ocasions for the same problem, every time was something different, as I was told by the service persons. On July 16/98 drove it to a different GMC dealer with the same problem a week after I pick it up and was informed they had to replace the ps pump. Still, to park the vehicle is a nightmare, you have to struggle with the steering wheel, like the old times when trucks did not have ps. Seems like a have a lemon but since in pr there is no lemon law I have no choice but to continue paying gmac in order to protect my credit.