Hello, I just came into possession of a 91 ford ranger manual trans 4 cyl. 2.3. I disconnected the negative cable of the battery. I replaced the plugs and wires and air filter. I checked and rechecked the gap on the plugs. I clean the throttle body with tb cleaner (it was very dirty). After all that, I start it up and blue smoke is constantly coming from the exhaust. I don't have any idea when they were last changed. Could the spark plugs be causing this? It calls for motorcraft awsf-32c(twin plug). Autozone gave me mc sp-493 agsf32pm. I am about at my technical limits with this. Any help would be much appreciated.