My dad owns a 1996 Monte Carlo Z34 (3400 Quad cam V6), it has a problem where its tempermental when you crank it over(doesn't want to start half the time, doesn't catch), the engine seems like its lagging substancially, and the transmission in overdrive it seems to lurch(also in 4th gear. if anyone can give me advice asap, i'd really appreciate it

 

the not catching could be a number of things but sounds like tune up time. plugs, wires, fuel filter are all good start if they are old and car has higher mileage, gm recommends every 100,000 miles for their best platinum or iridium acdelco plugs, and wires. try that if they are old or original. or spray the engine with water while its off and then try to start it if it won't go them you definatly need new tune up stuff.

 

If you get on the gas (floor it) does the car seem to lose power? (i ask this because i had a similar issue with starting up and the car loosing power when ever i stepped on it, it turned out to be the fuel pump going out and, of course the fuel pump went out when i was stopped at the busiest intersection in town during rush hour...)

I'd check fuel pressure and do a tune up (pretty much what justin said)