Idle Problem 1992 s10

When I idle at a light, the smooth idle is interrupted by a bump. I want to say I have a vac leak somewhere, trans fluid is getting to the engine (which has been happening), or the new spark plugs aren't properly gapped. I replaced all the vac hoses from the transfer case switch to the vac actuator, vac reservoir (black ball), intake, and cruise cont diaphram, and also the one-way valve to the intake. Idle still bumps. I've also noticed that after replacing the transfer case switch that fluid has still been escaping the case through the hoses, because I can see the fluid spread all over the case and every now and then, smoke from the exhaust pipe when I start the engine. Plus, the vac actuator was soiled with fluid and now needs to be replaced. I have a theory: The transmission to transfer case seal (rear main seal, correct?) is bad causing an exessive amount of fluid to travel into the transfer case, therefore pushing fluid up to the engine and other parts. How does that sound? I want to post a diagram, but apparently I cannot. How can I?Thanks.

i really dont see that happening. in order for it (trans fluid) to interupt idle, it would have to be in the combustion camber. is there any interuption when driving?
other things (and more common) to look into;
fuel pressure check
cap and rotor
plug wires
clean egr
timming

what engine do you have? 4.3 or 2.8

There is no problem when driving. I have a 4.3 L. The plugs, wires, cap, and rotor were installed in August. I've also about taking out the plugs and double checking the gap in them. I've never cleaned the EGR. How would I go about doing that? How do I do a fuel pressure check? I've tried to set the timing. I was told for my blazer the timing mark on the harmonic balancer should fall between the large notch, with the advance unplugged. Any advice on that?
Thanks.

you want to set timming at 0 degrees. what you should first is get some white out and put it on the mark on the balancer and the o degree mark. its much easier to see with timming light. then in passenger side under the capet, there is a brown wire, unhook it(thats you advance). ours dont have vacuum advance its eletrical. then set timming following a manual.
fuel pressure check is easy. youll need a fuel pressure gauge and a manual for your truck.
egr is located behind and beneath the throttlebody.
youll need to undo the fuel lines from throttlebody. i think its a 1/2 inch socket to remove the 2 mounting bolts. when youhave it off tap the plunger with a hammer to remove carbon biuldup. tap not hit.

Can you be more specific about the location of the timing advance? I was told it was a wire crossing above the brake booster.

no no no. its a brown wire that runs through the firewall on pass side, under the carpet and up behind glovebox. its brown,i think with white strip. been awhile since worked on timming in a older s10. but am very sure on location.
i have a 91 4.3 tbi just like your 92. most the wiring going over the booster is eigther going to dash, fusebox or to the cruise control. all on drivers side.

Ok, thanks. I'll look for it. One thing though; when I unplugged this wire I used before, it did alter the timing once I put the light on again. So, I think I'll have to double check both these wires.