Have trouble getting our 1997 chevy venture to start when the engine is cold

First have you had the electronic engine control system tested for trouble codes? if not that is the very 1st thing to do, most Autozones and Kragen will do this test for free, the next thing to do is have a fuel pressure leak-down test run, this will require a special fuel pressure test guage that goes to a test port at the top of the engine near the fuel injectors, if the test shows that the fuel pressure bleeds down more than 5 PSI in one hour then the fuel pump is defective and must be replaced due to a failed fuel pressure check valve that is part of the fuel pump, the next test you need done is to have a full function scanner hooked up and look at the ECT (engine coolant temperature sensor) to see if it is out of range, if it doesn't read the temp right the engine is very lean on cold start, both the above problems cause long engine start times, that is to say the engine cranks over but is slow to fire up, the next few things should be verified to rule them out as possibility's, is the engine starter turning the engine over fast? if not have the battery and starter tested, next are u using the correct grade of fuel, premium fuel put in a engine that uses just regular causes hard start in cold weather.