Toyota Repair: 1987 Toyota RPM problem


Question
QUESTION: I have a friend that has a 1987 Toyota 2WD, 5 speed manual pick up, with a carburetor. She is a single mother with little money to invest in getting this truck to pass emissions inspection, so I need any and help trying to determine what is wrong with little cost as possible.

When you rev up the engine in neutral the RPM goes up and down, so much that they can not do a emissions test since it will not run at a steady RPM to do the test.

I am almost certain it is somewhere in the carburetor system (I know how much this involves and could involve ), I just need to know where and what to check/look for.

ANSWER: Hello, does the engine idle normally?
Does the check engine light stay on?
Do you know how to check for trouble codes?

---------- FOLLOW-UP ----------

QUESTION: IT idles OK at low speeds, and it is steady at this range, but it does not have a tach to see at what RPM, or if it is unsteady.

I replaced the plugs, rotor, and the dist. cap. as far as engine goes so far.

I have a code reader for my 2011, but I do not know if it will connect to a 1987 model, or where.

This does not have a check engine light, but the oil pressure, charging system, and temperature gauge all seem to read normal.

It does seem to run hot though. Even when it is idling and has not run all that long the air coming out of the radiator is what I think is abnormally hot, uncomfortably hot. No overheating so far, even though it has been in the mid 90's here. The water is circulating through the radiator, visually anyway.

It runs generally well on the road. It has what seems to be normal pick up and power, she has not had it long enough to tell you what the gas mileage is.

Answer
The newer code reader won't connect to this system, does the check engine light turn on when the key is turned on?
If it does and then goes off after the engine runs it's most likely not anything to worry about, the 87 should have the EFI engine are you sure it has a carburetor?