I picked up an 89 Blazer 350 TBI, 700R4, 4x4 with 95,300 original miles which is bone stock down to the stereo. When I got it, it had a few maintenance issues, but I was more than willing to deal with those to have such a clean, non-beat-up rig. I did all the normal stuff by replacing all the old fluids and filters with new stuff...everything--engine, tranny, diffs, t-case etc. Here's the problem--it surges. It does it in all the gears, but it very apparent when cruising in say, 1st gear around 15mph, or in 2nd gear around 30 mpg. When you romp it, it will take off pretty good, but if you ease into the gas the power seems to come on in stages. I just can't figure out what the hell is causing this--it's freaking annoying to say the least. Here's a list of what has been repaired/replaced: -Cat converter/muffler/exhaust pipe--the stock stuff was trashed -New fuel filter--old one almost plugged solid -New Cap, rotor, wires and spark plugs -TBI torn apart, cleaned everything and put back together with new gaskets etc. -Checked all the hard vacuum lines and replaced what was bad -PCV Valve replaced -EGR Valve replaced(AC Delco unit) -O2 Sensor replaced There is no "Check Engine Light" coming on. It starts and idles fine. It accelerates fine when you romp it, but surges when accelerating at a moderate pace or when cruising. Any ideas? HELP!! TIA.