I have a 94 rodeo with about 230,000 :eek: (i know) miles on it, 4WD. When you start it it's fine. Then when you cruise to about 40-50mph it sputters, like puts along with no power, then black smoke comes out-if you really try to give it some gas. then once you get to about 55 then the "check engine" light comes on then the power kicks in. But if you turn off the engine you'll have to go through the process again. The plugs and wires have been changed. The catalyic convertor has been cleaned. Oil and filter have been changed, even upped the weight of the oil from 5-30 to 10-30 (no more ticking though. :grinyes: ) But other than that it runs fine and sounds healthy. I just don't know why it takes awhile for the power to kick in. Got any ideas.

You need to check what codes are setting in the computer. I seem to recall in some instances that if the ECM can't get the information it needs from certain sensors, that it will default to a predetermined set of parameters. Something the ECM deems important is not sending the desired information.

There is a little white 3 pin plug under the drivers side carpet, I think you need to connect the two outside terminals with a short piece of wire, turn the key to the on position (not start) and count the flashes of the check engine light. It will give a series of two digit numbers, 12 being displayed three times first. Then each stored code will be displayed three times each. You read the codes by counting the flashes, "FLASH pause FLASH FLASH longer pause" will give you code 12. "FLASH FLASH pause FLASH FLASH FLASH longer pause" would be code 23, for example. Remember, each code repeats intelf three times, then goes to the next code and it will always start and end with code 12.

Get the codes and post them here.

Sounds like you're running rich. If you don't get it fixed you'll need a new cat. Does this year have a MAF sensor?

it's your o2 sensor bro, just went through all the same things on a cross country trip and it caused havoc, came to all the forums on teh net, and everyone said same thing, ti's the o2 right by cat, mine only gives me problems after about an hour of driving, so i've yet to take care of it, but i hear electronics cleaner (forgot what particular brand was recomended, q something.... qd.. cant remember) works wounders, beats spending 50 bucks on it ya know.