Hello, im stuck & not sure what to look for?? its a 96 bravada ive done a tune up a few months ago, just replaced the distrbutor, cap & rotor, i changed the tps from a working blazer i also replaced the spider injectors, all 4 o2's been replaced, so when im driving the rpm will either nose dive then pull back to normal or when im driving on the e-way the rpm shoots up from 2000 to 2400 then back down to 2000 but constantly then ill shut the trucknoff and it wont start u have to crank it for like 5-10 sexonds a few times before it will start any ideas?