I have a 2000 2 door blazer 4x4 with a 4.3. For the last two years (except for the last couple months) i have had to spray start my moter with break clean, engine clean or starter fluid (i know, im an idiot). Finally swapped out the fuel pump (with filter and relay) and got it to start consistently. After some shifting issues and a TPS code i replaced the TPS sensor. Thats when the trouble started. Now my oil pressure is inconsistent. I replaced the sending unit and changed my oil with marvels mystery oil and a new filter. Some times the guage shows 60 psi at idle and dosnt change regardless of RPMs untill i have driven it around the block a couple times and it starts to read normal. Other times (though not since the oil change) it would read 60psi and ANY manipulation of the throttle would send the reading off the charts. I assumed it was due to an obstruction and when the motor warms up the reduction in viscosity allows the oil to flow naturally. Heres the twist that may or may not be related. I also have an engine tick/knock. Its extremely temperamental! Some times its not there at all. Other times it dosnt go away. More offten then not it Will only last a couple seconds then go away or it will stick around till i get on the freeway and will go away ofter 10 or 15 miles at 60+ mph. I was thinkin exhost leak. Being that i spray started it for so long maybe that repetitive explosion broke a bolt on the manifold or wore out the gasket. But i am still learning as i go and am open to ANY input! The truck has about 291,200 miles all of which where driven hard but well maintained (till i started spray starting it every morning). New parts are the battery, Fuel tank, fuel pump, fuel filter, fuel pump relay, TPS sensor, oil filter, fresh 5w 30 oil (with marvels), oil pressure sending unit, air filter, mass air flow sensor, distributor/cap/roter/plugs/wires and EGR valve.