I have a v.6.3 litre 93 verada.190000 klms.engine developes bad miss it seems when outside temperature is warm..changed dist. cap and leads but still same.last week was backing out my driveway and it developed the miss.hadnt used since night before.outside temp.was 28 deg.c. i turn off eng.for 5 mins its o.k. but will eventually do it again.the engine is perfect otherwise.

I saw your post and hope more Experts will follow to answer. There are some controls which use engine temperature to set fuel mixture. Some engines have 2 temperature sensors, one for engine controls and second for dash gauges. The signal from the temperature sensor goes into the brain module and then controls like idle mixture and running mixture are set.

Your problem with black smoke out exhaust would seem to show a rich mixture, like a stuck choke does, but the electronics are used to choke the engine. Either your truck is missing the temperature information, the module is not thinking about correcting engine settings or the solenoids are not responding to the module.

The cheapest part in the process is a temperature sensor, possibly a water thermostat for good measure to insure the water temperature is correct for the new temperature sensor. Usually other things like O2 sensors will throw a code if exhaust is too rich, a bit confusing if no "check engine" alert is present. Hope this helps.

Have you check to see if the timing on the car is right?

it could be a bad slav clinder

Please about the diagnosis and repair of engine misfires here.

Definetly sound like a misfire, possibly leads on incorrectly, or bad leads/spark plugs.....definetly explain lack of power and shakiness

a bad cat will cause it not to rum faster than 45mph. usually miss at warm after over taxing is bad camshaft. you probably knock the lobe down. you need to do a compression test on all cylyinders. they need to be reading close to each other. also just make sure plugs and wires are good. cap and rotor also

usually on these cars its the ignitor in the disrtibutor,take the cap of and see what manufacturer made the ignitor(hitatchi,nippon denso,mitsubishi,etc..)any parts store should have it in stock,there should only be 2 screws holdin it in the dist.,also if there is a red coloredpowder all over inside the dist. it should be replaced also. another problem could be the main relay which is another common problem,its mounted under the drivers side dash next to the steering column about knee height,its alittle bit of a pain to get to,its about 3" long and 1" wide,its big for a relay so its kinda hard to miss,give it a whack while crankin over the car and see if it fires up,if it does i believe this relay is still a dealer item,hope this helps

Have them put the timing back and see if the problem goes away. Ignition timing that is too far advanced will cause a no crank condition when warm.

The fault could be in the ingnition module in the dist.I had a car one time that did the same thing but when it was cold,try replacing the the ignition module.

HAVE YOUR EXHAUST CONVERTER CHECKED! IF IT'S BAD AND YOU HAVE IT REPLACED, DON'T LET THE ONE THAT REPLACE'S IT TAKE YOUR OLD ONE!!!!! IT'S WORTH ABOUT $250.00