if the plugs you took out of the truck were worn wide enough (the gap up from >.040) and they were causing the misfires (most likely culprit for the shaking from what i know) and the new plats are not doing any better they will cause the same misfire so change the plugs first, but there a couple of sensor on the engine you could try changing before going to the shop, if it was throwing any CEL codes that would make our life much easier,

if the light is on follow the procedure in the CEL thread stickied to the top of the forum and let us know what codes it is throwing


btw you could also put a bottle of fuel injector cleaner in the tank next time you fill 'er up and see if maybe you have a partly clogged fuel injector

 

right now i dont even drive it because it makes you wonder if you are even going to get back home in it---i may bite the bullet and change the plugs again,but i just cant believe that completly worn out plugs and these would cause the exact same thing?as far as the light--i have wondered about that because it has never been reliable--i have had it to go off and then they could not get it to read a code,and i have had bad parts and it not go off at all---could the cat convertor not cause this?---thanks

 

another idea --could it be the motor mounts or am i just grasping at straws now---thanks

 

ok--i went out this morning looking again and i got about pissed and floored the gas pretty good a couple of times and then it quit shaking,i went down the road and back and it seemed fine?---now who knows how long this will last,but just wondering about any ideas of why it cleared up like that---i had the sea foam in the tank,maybe it cleared up an injector or something?---anyway i also noticed that the harmonic balancer looks like its warped?--maybe i need to start a new thread on that---but any suggestions on the other---thanks

 

I resolved some strange idle and low speed driving problem by replacing the speed sensor.

 

Check your egr vavle, carbon can get stuck in the valve causing an internal vacume leak. You also need to check for a regular ol vacume leak. either will cause a problem up untill the engine pulls enough to negate their effect, or in the case of the egr valve, catch up.
Do you have a check engine light? is the engine comming up to temp properly. a stuck open stat or one of a temp not programed for will cause drivability issues as well.

 

definatly sounds like a miss fire but do a compression check just in case mine felt like it was missfiring but the mac said no misfires then it blew up