Hello I'm in need of some help here! I have a 2000 GMC jimmy 2 door 4wheel drive. My truck has been acting up. When I start it it revs up to about 2000 rpm and drops down to 1000rpm and drops down to where it wants to stall and jumps back up and does that. I will back out of my drive way and put it in drive and hit the gas and when I press the gas it just kinda chuggs along kinda like it missing like my truck kinda jumps and shakes. I got my plugs changed right before Halloween and that didn't change a thing in the way it runs. So I just got a starter put in last week amd i told the mechanic about it and he looked at it and he said he hooked up a vacume line that was in hooked. So when they called me to come get it I got in it ad it ran awesome. But 2 days later it started doing it again and the check engine light came back on..2ndly my 4wheel drive isn't working either. I really need help thanks!!
