Trouble Codes?

My 95 5.0 HO is putting out an 181 and a 189 trouble code. According to the book that means the system is running rich. Where should I start testing sensors? I have adjusted the timing and it is correct. The car has never run right. It feels like it it just won't get up and go.

O2 sensors and the ECT sensors are the biggest factor to the a/f ratio.

The above are good suggestions. Might want to check your TPS voltage, too. Closed it should be less than 1 volt - somewhere between .90 and .99. I run mine at .98. You will need to probe the wires. It's a three wire hook up and, as I recall, it's the green and black ones?? Running rich does sound more like 02 sensors, though. Or, you cats could be clogged, too.