Truck Repair: My Dodge Pick Up Truck, throttle position sensor, blue clouds

Question
Its a 1989-318cu-F.Injected-Whats it doing?-It's loping at an idle-sometimes-its loping at an idle so bad when I come to a stop (its automatic/odrive) at a light, that sometimes it dies-I can feel it surging even at freeway speed-my mpg has gone south-when I gas it in Park, heavy blue clouds/smoke-smells like gas-neighbor says catylytic convertor clogged-gut it out he says-illegal but you can get away with it thing-i tried chemtool for the gas-for the injectors-no improvement at all-fixing to try Bardhal No-Smoke I guess- in the past a mech told me my compression was not so good-the no smoke may seal enough stuff to reduce the smoking-maybe. my idle has never been right-could it just be that?-cause it runs perfectly sometimes-outta the blue it will just take off running perfectly-anyways, thats it, any advice would be greatly apprecialted. Thx............Ray.

Answer
Check all the wire connectors for loose. I doubt the converter is the cause, but it will get plugged if it runs long like that.
The throttle position sensor, or vacuum sensor could be bad, but there should be a service engine light if so.
If you want to check for stored fault codes, use the key. Here are the steps.
Turn the key to run, off, run, off, run...about the speed you read it.
Run, but not to crank.
Then that third time, leave it in run, engine off, and watch the dash lights.
One of them will start to blink.
Count the flashes. Blink, Blink, Blink, pause, Blink, blink  for example is 32.
It should do it a couple times. See what they are. 55 means end of test.
Then look them up, and see where they point you.

This link may help.   http://www.autotap.com/obdii_library.asp

Van