The intakes looked normal to me. Im far from an expert, but there was nothing staring me in the face when I inspected them. I used 2 brand new sets of bolts from felpro with felpro gaskets. Long bolts under the valve cover, medium 2 in the front and back, and shorties under the exhaust manifold. 3 passes and everything seemed to torque ok. Chased the threads in the block beforehand, cleaned with solvent and a wire brush. I didn't notice any warping or cracking in either mating surface. I just started the truck a few minutes ago, and it ran rough for about 30 seconds and is currently running just fine. That 30 seconds was enough to flash the MIL throwing p0302. Should have left well enough alone before haha. Well off to work, I will continue to update.

 

A code P0302 may mean that one or more of the following has happened:

• http://www.obd-codes.com/p0302
• ~

 

Another update, and possibly the last on this thread. Gas mileage has seemed to hold steady right under 15MPG. Just filled up today and got 14.8 average again, and did a little more city driving than usual. As far as mileage goes, this is not where I would prefer it to be, but all in all, I can't complain too much, as it has improved by ~50% from the lowest. You guys have all been a ton of help, and I appreciate it greatly. I will not be around very much for the next few weeks, as my son will be born in early March, and I will be preparing around the house (and mentally :P ) Once things settle back down, I will return, and if all goes according to plan, start a build thread with my little 230K mile L35 sitting in the garage. Big ups to BF and to all the wonderful people and information made readily available. Thanks again to all!

 

According to Edmunds, 1999 blazers are supposed to get 15 city/ 21 highway...I'm not sure if that applies to other years, but I thought I was having problems too, and it turns out I'm getting 14.5 mpg, even when driving like an old geezer in the city.

 

14-15mpg in the city is average for these Jimmys.The Hyway milege will vary depending on the year 18-21mpg.
I have 94 regular cab truck with the 4.3,4L60e auto,308 gears.I get 12 city and 18-19 hiway.It was better,maybe 14 city and 20 hyway.
I get better milege on the top half of the tank when its full and much lower on the bottom half.