Truck Repair: Excessive fuel comsumption, air fuel mixture, chevy 4x4

Question
QUESTION: I have an '89 Chevy 4X4 1500 w/350 and auto trans.  It used to get good mileage,17-19mpg and now it is doing very poorly 1/8 of a tank to 30-35 miles. I have replace the complete fuel system from the TBI to and too include the tank.  I have checked all the sensors and they seem to be in spec.  I have installed new injectors and regulator in the TBI.  But hot or cold, it stills smells rich coming from the exhaust.  I really could use some help here.

ANSWER: Hi Dale,
Simple first, have you checked your air filter? Next check your timing and make sure it is to factory spec. It could be the catalytic converter plugging up....are you lacking power? Make sure the MAP sensor is within spec. Check all your vacume hoses..if you have a leak it may send things out of wack. It is odd that it hasn't tripped a code...usually if the O2 sensor can't compensate the air/fuel mixture it will log a code. My suspicion is that the timing is out to lunch...possibly worn distibuter drive or timing sensor out of spec.

Good luck,

Matt

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QUESTION: I have done all that, the map sensor according to the scanner was fine. It will not trigger a code.  I removed the Cat and installed a test pipe and it still didn't make any difference.  I think it maybe to old for timing sensor or I don't know the location.  Could I have a cracked intake manifold from the under side where I can't detect it?

Answer
Hey,
I did some digging and found that if the CTS (coolant temp sensor)is not working properly it will tell the computer to richen the fuel mixture so warm up the engine quicker, if it reads cold all the time then it will run rich. find some specs for this sensor and see if that is the problem