The 87 Ranger I recently acquired has a 2.9 and it ran really rough. I have found several possibilities but I have not put it back together yet. One thing I am addressing is the EGR valve. The port in the air plenum was so clogged I needed a half inch drill bit to clear it. It was clogged all the way through. I pulled the EGR valve off and it is in good shape, but was clogged and I cleaned it as well. Then I found the tube that runs from the exhaust manifold to the EGR valve is also completely clogged. I get what the EGR valve does and how it works. However, I do not see how all these parts can get so clogged. What would cause this, and what kind of problems will the truck have has a result? I have deleted mechanical EGR valves on old trucks like this before; but is it a good idea?

 

Engine was probably not serviced regularly.
i.e. changed oil, spark plugs and air cleaner.

These all effect efficient combustion, when it isn't as efficient you get carbon residue, that is what clogged EGR tube and valve.

EGR system is there to lower combustion chamber temperatures when engine is under load, not to reburn exhaust gases, lower temps reduces NOx emissions, side effect is engine won't ping with advanced timing on regular gas.
If you delete the EGR system your engine may ping/knock under load, on carb engines you could just run engine richer or retard timing.
On EFI engines the computer expects EGR system to be working so you may get pinging when accelerating or climbing hills, and may have to retard timing(so spark happens sooner), this reduces MPG and performance.

 

Gotcha. I knew it could be done on older engines. I agree with the lack of maintenance. The previous owner did not understand such things.