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1988 GMC S15 with 4.3L engine, I am looking for the voltage reading between b and c at the connector(wiring harness) the 307 is at .525 the 2.5 is around .800 but I need to set a 4.3 and do not have the voltage setting. Thanks for any help  

with the throttle closed...   you should have just over half a volt ... but less than 3/4 volt...

there is a problem...  the throttle shaft bores wear on some throttle bodys...      with the engine off..  open the throttle by hand part way.. see if the shaft wiggles around at all...  you can only see this with the throttle open part way.. with it closed.. the throttle will be wedged tight by the throttle blades..

if you turn the key on... and work the throttle  a bunch of times...  the throttle position sensor voltage needs to come back to the exact same voltage every time... when the throttle is closed...   if it varies... you will have problems... as the ecm never knows when the throttle is actually closed...

are you having problems with the engine at fast idle...    that won't drop?????    if so.. change the thermostat... they take a 195F thermostat....   the last digit on the part number at the store will usually be a ____9   this indicates that it is a 195 thermostat..

if the stat is removed... broken.. the wrong one installed..  the ecm looks at the coolant temp sensor ... if it does not see a steady increase toward normal operating temps above 190F ... it will keep the idle air control motor retracted.. as it is trying to warm the motor to operating temp..

back to the throttle shaft bore wear.....   a lot of carb rebuilders have started rebushing the throttle shaft bores... to fix this...
be sure to ask them if they do it... not all ***  the screws that hold the throttle blades on have the ends damaged to prevent them from backing out and falling into the motor... if someone tries to get them out without grinding the exposed end off...  they will break off in the shaft...  they are too small to drill out..  2.5mm x .45 pitch X 6 mm cheese head screws..  so they are also really hard to find replacements for...

all this and i did not find the tps spec exactly.. i just don't have that book handy...  

well thank you for your reply, I got a reading of .225 though I did not try moving the shaft around, I did not even think of bore were, I will check that tomorrow.  I replaced timing chain, the truck was towed in so I had no idea of all that might be wrong. they had the dissy out and lets just say I am  going from scratch checking all I can with out being a parts changer,the people have little money you know how it is. today I tried to start unit but only a short cough not really a solid hit. rechecked tdc and dissy and they are good to go, seems to have a drag in the starter but most of all the fuel just dose not seem to be pulsing from TB with much gusto,I have a fp gauge but I need a T to fit the hard lines at in port, will try to make one tomorrow. The fuel relay is doing its thing just fine, will pull fuel filter and try to get a pressure reading, the only other thing I can think of is that the oil sensor may be bad, what do you think?  thanks again my brain is stretching....