Hey Scotty. I have a 1999 Cadillac Deville. I've watched a lot of your videos on Mass Air Flow cleaning and hesitating acceleration as well as videos on what to do if your car doesn't start up on the first try. I have been having issues with my car. It seems to start perfectly every time first try in the morning. But after I get to work and any time after that, it will only start up after holding the key for a looooong time, or if i give it some gas. It has also been hesitating when I pull off from a stop light but after about 40 mph the hesitation goes away and shes gone. The only other thing is that I've been feeling a weird bump or jolt or something coming from either under the hood or under the car, it had been sporadic up until last friday when I was driving home I stopped at a light and she just started doing it over and over. Some kind of weird vibration underneath the hood or something. Also the other day when I tried to start her up, she backfired and popped under the hood, it smelled really bad and there was a puff of smoke. I recently changed the spark plugs out and the crankshaft sensor, new radiator, new coolant reservoir, not sure what to do. If you are in Texas can I just bring it to you!? I live in Austin!!!!

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well, do check for a broken motor mount, but those caddies are notorious for blowing head gaskets. Do this video test FIRST https://www.youtube.com/watch?v=QA7KVQq9vKA&t=7s