I have a 1999 Cadillac Seville, when my car is cold and I take off right away it will hesitate. If I let it sit and warm up or if it has been driven recently I do not get this hesitation when taking off. I tried the fuel injector product you put in your gas tank, but it did not seem to help.
The car has 120,000 miles on it. I bought it at 88,000 and have not done anything to it except change the oil.
My husband recently started using synthethic oil in it. Could this be the problem. I only use premium gas. I am thinking it is more with fuel injection.
Any ideas on what the problem may be?
Look at the Owner’s manual. You’re overdue a tuneup and a new set of plugs. And filters. And probably a few other things.
I was wondering about a tune up. Thanks…
The last time your air filter was changed, the fasteners may have been left loose or an air duct might be off or loose. The hose from the air plenum to the exhaust stove may be broken or off. The ported vacuum valve may be broken and can’t close the heat regulator butterfly. The diaphragm from the actuator may be broken. One of the electronic sensors may have gone bad. Vacuum leak at the throttle body.
You might consider the fuel filter also. If it’s partially clogged the car may normally run fine but fuel volume, not pressure, can be affected.
A cold engine requires more fuel than warm one so if the filter is not flowing enough gas volume the engine could be suffering a lean hiccup.
A weakening fuel pump can do the same thing.
If you change the fuel filter, drain the old filter and allow it to dry for an hour or so. Wipe off the end and try blowing through it. If you cannot blow freely through it then it’s clogged. A clogged filter can also be detrimental to the fuel pump and cause early failure.
Or talk hubby into performing this test. Most men are impervious to toxic chemicals. 
The air duct that runs from the air filter to the engine was cracked all the way through and just hanging there. This was our problem. Thanks a ton.