1995 Isuzu Rodeo Backfireing Intake Manifold And Hesitation!!
 

Hi, I have a 95 isuzu rodeo 5 speed manual. It just had a full tune up. Now, the issue that has been driving me nutts for about two months of working on it is that it has a hesitation/backfireing from the intake. When I go wide open throttle in neutral the car bogs pops and hesitates till 1500 RPM's and sometimes it witll go up and down there and pop/backfire from the intake manifold. Now, when I rev it for about a half hour starting from low to high RPM it revs and runs like a dream till I try to drive it an hour or two later. This is the only way to make it run good, the revving and getting the backfireing out. This is starting to drive me crazy after three months. There is no check engine light, but when I ran a scan on it, it said it was running lean and something with the o2 sensor. So the car has new bosh plugs, wires, o2 sensor, fuel filter, air filter and so on. I even changed the TPS and cleaned the EGR valve. I have tried multiple additive treatments and all. This has been driving me nutts for two months now. And the only thing that seems to make it run good for a while is for me to rev it for a halfhour till I guess it gets hott enough and there are no more back fires coming from the intake area. The car actually passed NJ inspection recently, but I had to do the whole rev thing to get it running right in the parking lot lol. Any help or insight on this would be very very much appreciated. Thanks in advance!!