try the solenoid controlling the egr
You may have a problem with the transducer. Check the wires coming from the transducer. If the connection is not loose and everything is okay, you will have to replace the transducer.
How often you should change your air filter depends on how much you use it. If your air conditioner is not blowing enough air. That is generally a good sign that it needs to be replaced. After you replace it, continue to check it regularly and replace it whenever you think it needs to be replaced
It is recommended that you check your belt twice a year. If there are any cracks or it is dried out, it should be replaced.
replace only when u get a check engine light. the valve is good for the life of the motor(should be)
Replace the fuel filter & air filter. If you have never replaced the spark plugs, do so.
When you replaced the fuel pump did you replace the short fuel line from the pump to sending unit? I didn't when I replaced the fuel pump on my 94 Safari and I had that problem. Also check to see if the pump is running when you turn the key on it should run for a few seconds. If pump works replace fuel filter. If still no luck check the fuel pressure. It should be around 80 to 100 psi.
A code 194 means cell dirty (needs cleaning) or needs to be replaced. You can try cleaning to out, check the manual for instructions but before replacing it double check the cord connections and if you replace the cell you should replace the cord as well.
If you haven't replaced the relay, check this website. It will show where it is located and how to replace. autorepair.about.com
Check and see if there is a shear pin on the shaft of the wheel you removed if there is it has probably fallen out and you will have to replace then it should work.
Did you replace /check the seats also?
Check or replace the socket
First, remove all encroaching vegetation. Then, replace rotted wood and broken support structures. Windows and entrances should also be replaced to guard from moisture and the inevitable mold that comes with it. You should check the wiring, load bearing structures, and Plumbing.